[sdk validation] Return an error if package-dir is added under any emitter options in tspconfig.yaml

Since we're actively working on deprecating all package-dir usage in tspconfig.yaml files, we should ensure that nobody tries to add that option back into the tspconfig.yaml file. If they do, there should be a PR check that fails.

@raych1 can you help take a look at this?

Locate the tspconfig.yaml validation and the PR check that reports configuration errors; start by tracing how emitter options are parsed and validated. Add coverage for package-dir under every emitter option, and confirm the PR check fails when that option is present.

Written by the indexing model from the issue text.