[Maintenance] Update formatter to match modern Skia

Based on an analysis of the 100 most recent C++/ObjC commits, update .clang-format (in both the Cpp and ObjC sections) with changes that reflect modern Skia style choices.

- Add StatementMacros: [ SkDEBUGCODE, SkDEBUGF, SK_DUMP_TASKS_CODE ] so macros invoked without a trailing semicolon do not cause clang-format to misparse and indent the following statement or declaration.
- Set BreakStringLiterals: false to avoid splitting long string literals (such as _Pragma strings and test pipeline descriptions).
- Set ReflowComments: false to preserve manually formatted comments.
- Set KeepEmptyLinesAtTheStartOfBlocks: true.

Change-Id: Ia1a4f935ed269b3b67792c2daa814ee269a3d67d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1380297
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Alexis Cruz-Ayala <alexisdavidc@google.com>