This extends the --dns option support to the start-lambda command,
allowing users to specify custom DNS servers when running the local
Lambda service endpoint.

Example usage:
  sam local start-lambda --dns 8.8.8.8 --dns 1.1.1.1

The dns parameter is threaded through the start-lambda CLI to the
invoke context, consistent with the implementation in the invoke
command.

The --dns option is only needed for sam local start-lambda and not
for the invoke command. This removes the dns parameter from the
invoke CLI while keeping the underlying infrastructure support
for start-lambda.

- Add integration test (test_start_lambda_dns.py) to verify DNS option
  works correctly with sam local start-lambda
- Update unit tests to include dns parameter in test assertions
- Tests are not marked as tier1 to avoid running in all PR workflows

The integration test verifies that:
1. start-lambda service starts successfully with custom DNS servers
2. Lambda functions can be invoked when DNS is configured
3. Multiple invocations work correctly with DNS settings

- Add smoke test (test_invoke_function_with_custom_dns) that verifies
  DNS flag is accepted and functions invoke successfully
- Add container inspection test (test_dns_configured_in_container) that
  checks Docker container DNS config using container.attrs['HostConfig']['Dns']
- Container inspection follows pattern from test_start_lambda.py
- Note: Container inspection may have timing issues in some environments
  as containers exit quickly after execution

Updated unit tests to include dns parameter

Remove redundant comments and flaky markers from test methods.
The tests are stable and don't need reruns.

Change dns parameter type from Optional[list] to Optional[tuple]
to match the actual tuple type passed from CLI (Click multiple=True).
The conversion to list happens when passing to Docker SDK.

This follows the same pattern as other parameters where Click returns
tuple, which is then converted to the appropriate type for Docker.

This change adds support for custom DNS server configuration in Lambda
containers when using the 'sam local start-lambda' command. Users can now
specify one or more DNS servers that will be configured in the Docker
containers running their Lambda functions.

Usage:
  sam local start-lambda --dns 8.8.8.8 --dns 1.1.1.1

The --dns parameter can be specified multiple times to configure multiple
DNS servers. The DNS servers are passed to the Docker container and will
be used for name resolution by Lambda functions.

Testing:
- Integration tests: test_start_lambda_dns.py verifies containers are
  created with correct DNS configuration
- Tests are NOT marked as tier1 per recommendation

Moved --dns option from shared docker_click_options() to be a
command-specific option for sam local start-lambda. This avoids
the need to add tests for sam build, sam local invoke, and
sam local start-api commands.

Changes:
- Removed --dns from docker_click_options() in _utils/options.py
- Added --dns as a click.option decorator directly in start_lambda/cli.py
- Updated unit tests to include dns=None parameter in assertions
- Regenerated schema to reflect DNS only in start-lambda command
- Applied code formatting (black) to integration test and runtime.py

All 6,959 unit tests passing.

The invoke() method signature was missed during the initial rename.
This caused a TypeError when calling invoke with container_dns parameter.

Fixed by renaming:
- Parameter from dns to container_dns in invoke() signature
- Parameter in docstring
- Usage in create() and run() method calls

When using --warm-containers EAGER mode, containers are pre-created
during service startup in _initialize_all_functions_containers().
This initialization was missing the container_dns parameter, causing
DNS settings to not be applied to eagerly-created containers.

Fixed by adding container_dns=self._container_dns to the runtime.run()
call in the initialize_function_container() function.

Add integration tests for sam local invoke and sam local start-api to verify
--container-dns option is properly wired through and DNS configuration is
applied to containers.

- test_invoke_dns.py: Tests for sam local invoke with --container-dns
- test_start_api_dns.py: Tests for sam local start-api with --container-dns

Both tests verify that:
1. Commands accept the --container-dns option
2. Functions execute successfully with custom DNS servers
3. DNS configuration is actually applied to Docker containers

Add integration tests for sam local invoke and sam local start-api to verify
--container-dns option is properly wired through and DNS configuration is
applied to containers.

- test_invoke_dns.py: Tests for sam local invoke with --container-dns
  - Verifies command accepts multiple DNS servers
  - Polls for containers during 10-second sleep to inspect DNS config

- test_start_api_dns.py: Tests for sam local start-api with --container-dns
  - Verifies API requests succeed with custom DNS
  - Inspects container DNS configuration after invocation

Both tests verify DNS settings are actually applied to Docker containers
by inspecting HostConfig.Dns in running containers.

- Remove unnecessary inline comments from test files
- Replace polling with fixed 7-second wait in invoke DNS test
- Update test_invoke_accepts_multiple_dns_servers to use HelloWorldServerlessFunction instead of TimeoutFunctionWithParameter
- Remove redundant comments that don't add value to code understanding

Merges all changes from feat/add-dns-option including:
- Rename --dns to --container-dns for consistency
- Add --container-dns support for all three local commands (invoke, start-api, start-lambda)
- Add comprehensive integration and unit tests
- Fix type annotations and parameter passing throughout the stack