[clang-format] Treat AttributeMacro more like __attribute__

There are two parts to this fix:
- Annotate the paren after an AttributeMacro as an AttributeLParen.
- Treat an AttributeMacro-without-paren the same as one with a paren.

I added a new test-case to differentiate a macro that is or is-not an
AttributeMacro; also handled whether ColumnLimit is set to infinite (0) or a
finite value, as part of this patch is in ContinuationIndenter.

Closes #68722.

Differential Revision: https://reviews.llvm.org/D145262