Add build and test workflow for PJRT plugin in pkgci

[PragmaTwice]

This changes are for adding the build workflow for iree-pjrt-plugin-* packages in build_tools/pkgci scripts.

Also, it enables the build of package iree-pjrt-plugin-cpu in Github Actions (pkgci.yaml).

Some other changes are for fixing some build problems:

• ninja is missing from pyproject.toml
• IREE_BUILD_COMPILER need to be enabled to make IREELLVMIncludeSetup available

It closes #19221.

ci-exactly: build_packages, test_pjrt

[PragmaTwice]

Hi @ScottTodd , thanks for your kindly review. Learn a lot.

I've refactored it to a separate PJRT build & test workflow now, feel free to give suggestions : )

Currently only the CPU plugin is enabled in CI (but the workflow is extensible itself, can just uncomment some matrix item) since:

• for CUDA the runner looks not available (maybe WIP?)
• for AMD sadly I don't have a device to verify on my local so I make it a TODO.

[ScottTodd]

• Edited the tags in the PR description to just ci-exactly: build_packages, test_pjrt since other workflows aren't affected by these changes.
• Approved the workflow runs

I can also send you an invite to iree-org so the checks will run automatically for your PRs if you want.

[PragmaTwice]

Thank you for your quick actions!

I can also send you an invite to iree-org so the checks will run automatically for your PRs if you want.

Ahh thank you. That would be great. I'll accept the invitation : )

[ScottTodd]

No problem. Caught me just before making dinner 😀 . Invite sent. Docs for access levels are at https://iree.dev/developers/general/contributing/#obtaining-commit-access