GitHub workflows should use more restrictive bazel cache line

Currently we use `{{ github.sha1 }}` as the main cache line for storing bazel cache in GitHub actions.

This effectively cause a new cache to be created on each commit eating precious cache quota and potentially slowing down the cache action post run step (as it need to upload a brand new cache).

https://github.com/actions/cache/blob/main/examples.md#---bazel suggests to use:
```
key: ${{ runner.os }}-bazel-${{ hashFiles('.bazelversion', '.bazelrc', 'WORKSPACE', 'WORKSPACE.bazel', 'MODULE.bazel') }}
```

We could use a derivative of this, that also include `dependency_support` bzl files to only re-upload a new cache when the project dependencies change.

This would have the side effect of *not* refreshing the cache of the main XLS build anymore, but that's not where we spend the most of our build time anyway.