[clang] [clang-format] Support of TableGen formatting. (PR #76059)

[Hirofumi Nakamura via cfe-commits]

hnakamura5 wrote:

@rymiel  @HazardyKnusperkeks 
Thank you for your review!
I have fixed the points.
But for refactoring of the test base class in https://github.com/llvm/llvm-project/commit/f8d10d5ac9ab4b45b388c74357fc82fb96562e66 .
I'm not sure I should do here, and if I should, I should do it in splitted pull request.

Now I really understand I should split this pull request into some parts. At first it is large and continue growing by adding documents.
I'm wondering how and current plan is separating semantically,

- Handling multi line string (~100 lines).
- Handling numeric like identifier (~100 lines). 
- Handling TableGen specific keywords (~100 lines)
- Unwrapped line parsing(~100 lines).
- Parse TableGen values (about 500+ lines including unittest).
- Basic options (but for aligning ones) (about 500+ lines including the document).
- Aligning options (about 100 lines including document).
- Refactor unittests.

I'm not sure this is good plan. They may be complicated.
Could you help me to plan if you have some idea?

In addition, I do not know the appropriate way to split pull request after I made one. Is it enough to refer each other, and abort this at last?

https://github.com/llvm/llvm-project/pull/76059