[Clang][CoverageMapping] Fix compile time explosions by adjusting only appropriated skipped ranges

D83592 added comments to be part of skipped regions, and as part of that, it
also shrinks a skipped range if it spans a line that contains a non-comment
token. This is done by `adjustSkippedRange`.

The `adjustSkippedRange` currently runs on skipped regions that are not
comments, causing a 5min regression while building a big C++ files without any
comments.

Fix the compile time introduced in D83592 by tagging SkippedRange with kind
information and use that to decide what needs additional processing.

Differential Revision: https://reviews.llvm.org/D127338