This removes embedded (single-file) and multi-threading modes.

Embedded mode is removed, as modern bundles provide multiple ways to embed binary resources and combine the ES modules, hence it's better to delegate that to the end-user. This resolves #139 and significantly simplifies our E2E tests, since we don't have to build and test the 2 versions of the package (embedded and side-load). This also removes the dependency on rollup in our MSBuild tasks.

Multi-threading support is removed, because Microsoft decided to remove the possibility of sync interop in WASM MT in a breaking way (dotnet/runtime#111098) and using Bootsharp over strictly async API surface does not make sense. This closes #168 and simplifies the boot resources composition, as we can now statically import the .NET's ES modules.

This also changes the boot signature: it now accepts the root URL string or the full BootOptions directly, for example:

import bootsharp from "./csproj/bin/bootsharp";

await bootsharp.boot("/root"); // boot with the root URL
await bootsharp.boot({ wasm: await fetch(...) }); // boot with preloaded resources
await bootsharp.boot(); // error - embedded mode is removed