[clang-format] Improve require and concept handling

- Added an option where to put the requires clauses.
- Renamed IndentRequires to IndentRequiresClause.
- Changed BreakBeforeConceptDeclaration from bool to an enum.

Fixes https://llvm.org/PR32165, and https://llvm.org/PR52401.

Differential Revision: https://reviews.llvm.org/D113319