grpc_credentials: remove well_known_names

[daixiang0]

Signed-off-by: Long Dai long0dai@foxmail.com

Commit Message:

Remove weel_known_names in grpc_credentials field, part of #7238

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[dmitri-d]

source/extensions/grpc_credentials/well_known_names.h (and similar in other PRs) acted as a sort of docs for the format of factory names. Is this documented elsewhere (I didn't see at a quick glance)? Should the format be documented, perhaps here: https://github.com/envoyproxy/envoy/blob/main/include/envoy/config/typed_config.h#L22? There's a comment there, but I don't think it's sufficient...

[mattklein123]

source/extensions/grpc_credentials/well_known_names.h (and similar in other PRs) acted as a sort of docs for the format of factory names. Is this documented elsewhere (I didn't see at a quick glance)? Should the format be documented, perhaps here: https://github.com/envoyproxy/envoy/blob/main/include/envoy/config/typed_config.h#L22? There's a comment there, but I don't think it's sufficient...

+1 let's do a follow up PR somewhere to document expectations here. Perhaps also here: https://github.com/envoyproxy/envoy/blob/main/EXTENSION_POLICY.md

[mattklein123]

Thanks!