[llvm-pdbutil] Dump and parse unknown records (#180761)
When new record types or leaf kinds are added to CodeView, then we
should try to dump all the information we have on these records.
- If a type or symbol is unknown, the raw data is now always shown.
Before, you'd have to set `--sym-data` or `--type-data` (but that would
show it for all types).
- Converting to/from YAML, unknown records are now included. Before we'd
error out.
I stumbled upon this when checking PDBs from C++ 20 coroutines compiled
with MSVC. These contain the symbol records `0x1171` and `0x117c`, which
we don't handle yet.
