Fix incompatibilities with Protobuf 22.x.

- Add missing headers.
- Modify libjsonpb to be compatible with std::string_view usage
  in Protobuf generated code.

Bug: 329747255
Test: presubmit
Change-Id: Ibeeb7b7dac66a7fb0189a1d13b36a853d3fcd3d4
3 files changed