[lldb] Use MemoryCache in Process::ReadRangesFromMemory (#201166)
There are scenarios (especially in the ObjectiveC metadata reading) in
which multiple strings are read over and over again, but through
different code paths. In order to make that part of the code use
MultiMemRead effectively, the memory cache must be integrated into
ReadRangesFromMemory before we can migrate the string reading to
vectorized version.
