[lldb] Add ReadCStrings API to Process (#172026)

This commit uses Process::ReadMemoryRanges to create an efficient method
for reading multiple strings at once. This method works like the
single-string version, reading 256 bytes at a time, but instead doing it
for _every_ string requested at the same time.

GitOrigin-RevId: e47b10917f8d7ca8edc8b096d502a0c2b3a901dc