.. and use that instead of importing the props file. This allows reading
the file on demand, and can be delayed till we have the runtime pack
path.

.. needed.

- Don't build samples, functional tests, and Wasm.Build.Tests on EAT, AOT lanes
- And build the samples in parallel

.. pack, instead of constructing it manually from nuget package path.

.. and add per-test timeout.

- Currently, the cross aot packages get built on CI for the various
  configs, but we do get the binary built in artifacts.
- These changes allow a package to be generated based on that, and it
  will be useful for installing workloads that use such a package.

Currently we run `Wasm.Build.Tests` on helix, by setting various paths to
reference files from `artifacts`. This PR adds another mode, we *try* to test
against workload packs.

For this:

1. we need the nugets for the various workload packs, and the manifests
2. manifest id, path to those nugets
3. and a SDK version to use for testing

Steps:

1. The specified SDK is installed in `artifacts/bin/dotnet-workload`
2. the specified manifest is installed from the built nugets, and any
   `depends-on` manifests in the json.

3. `dotnet workload install` is used to install the packs, with the built
   nugets path being used as one the nuget sources

Once this setup is done, the tests are run in an environment such that
they use `dotnet` from above, and try to resolve packs from there.

Known issues:
1. `Pack` target is explicitly invoked for the aotcross projects

We still want to test without packs, the case of using `EMSDK_PATH` directly,
for example, in the library tests. So, we now run `Wasm.Build.Tests` for
Workloads, *and* the regular `EMSDK_PATH`.

Two workload specific tests were added in a recent PR (dotnet#54936)
- simple test for building blazorwasm template project with AOT
- a test to validate that the files in `UnixFilePermissions.xml` for the packs actually exist on disk

.. and these are enabled here.

Notes:
- This also fixes using the correct runtime pack based on the version in the manifest json.
- The sdk version is specified with
  `<SdkVersionForWorkloadTesting>6.0.100-preview.7.21326.4</SdkVersionForWorkloadTesting>`
  in `eng/Versions.props`

TODO:
- Run the blazorwasm test with playwright
- Add sdk-with-no-packs case also

…ation fails

…ng corrupted by concurrent access