- Add
  `[assembly:System.Runtime.Versioning.SupportedOSPlatform("browser")]`
  to the browser, and console templates. This would allow the analyzers,
  if enabled, to treat the assembly as one that will run only on
  browser.

- Populate `@(SupportedPlatform)` with only `browser`, for *wasm*
  projects, similar to https://github.com/dotnet/sdk/blob/fef8cedfb6b4ac85a7e135f3e4f155e29cdcbdf1/src/BlazorWasmSdk/Targets/Microsoft.NET.Sdk.BlazorWebAssembly.5_0.targets#L75-L79

- This also fixes the firefox CI build which regressed recently