LSC: Add std:: qualifications to all references to std::string and std::basic_string.
Adding these qualifications will make google3 C++ more portable, allow the global using std::string declarations in the google3 copy of the C++ standard library to be deleted, and bring google3 C++ in line with how the rest of the world uses C++. This completes the work started in go/lsc-add-std and go/std-type-qualification.
LSC documentation: go/lsc-std-string
Tested:
tap_presubmit: http://test/OCL:296219821:BASE:296205992:1582238469429:4f5b2b3
Some tests failed; test failures are believed to be unrelated to this CL
PiperOrigin-RevId: 296825017
Change-Id: I2b41071f7f9cc790308a6c95270659dcd57e3a27
24 files changed
