See #36176. The only difference is a temporary shim for Secure credentials types, which was already discussed and approved separately.
Closes#36242
COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/36242 from drfloob:reland/36176 f07bebe289
PiperOrigin-RevId: 621879911
Forked from #35957
This PR refactors the credentials types to remove Secure and Insecure Channel and Call credentials types. We standardize on a `c_creds()` accessor method for all credentials types, which can now be treated uniformly. This notably removes special-case handling of insecure credentials.
The special code-paths for insecure creds are no longer necessary in the wake of #25586.
Closes#36176
COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/36176 from drfloob:fork/35957/creds-API fd64d59c23
PiperOrigin-RevId: 621008166
AJ Heller