Instead of wrapping `throwIfError` in a try/catch at call sites, add a
variadic overload that accepts a `fmt::format_string` context and appends
it to the exception message directly inside `throwIfError`. Update the
`listObjects` call to use the new overload, passing bucket, path prefix,
and disk name.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

…perations

Four call sites where listing or existence-check operations could throw
with an opaque error message lacking disk/container/path info:

- `AzureObjectStorage::listObjects`: wrap `ListBlobs` loop in
  `try`/`catch (StorageException)`, re-throw as `DB::Exception` with
  container, prefix, and disk name.
- `AzureIteratorAsync::getBatchAndCheckNext`: same pattern for the async
  listing path; pass `container` and `disk_name` through the constructor
  so the catch block has full context.
- `AzureObjectStorage::exists`: the existing `StorageException` catch
  already handles `NotFound` correctly; now re-throws other errors
  (e.g. `AccessDenied`) as a `DB::Exception` with object path, container,
  and disk name instead of a bare `throw`.
- `S3ObjectStorage::getObjectMetadata`: the existing `addMessage` call
  only included the object path; extend it to also include the bucket
  and disk name.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>