[llvm] [ci] ids-check: build tablegen headers for idt (PR #176415)

[Yaxun Liu via llvm-commits]

yxsamliu wrote:

Closing as superseded. The current [ids-check workflow](https://github.com/llvm/llvm-project/blob/main/.github/workflows/ids-check.yml) already builds the generated headers and each enabled target's `CommonTableGen` prerequisites before running `idt`, covering the build step this PR adds. Thanks for the review.


https://github.com/llvm/llvm-project/pull/176415