chore(oidc): graduate webkey to stable (#10122)

# Which Problems Are Solved

Stabilize the usage of webkeys.

# How the Problems Are Solved

- Remove all legacy signing key code from the OIDC API
- Remove the webkey feature flag from proto
- Remove the webkey feature flag from console
- Cleanup documentation

# Additional Changes

- Resolved some canonical header linter errors in OIDC
- Use the constant for `projections.lock` in the saml package.

# Additional Context

- Closes #10029
- After #10105
- After #10061

internal/api/oidc/server.go

@@ -188,7 +188,7 @@ func (s *Server) createDiscoveryConfig(ctx context.Context, supportedUILocales o
 		},
 		GrantTypesSupported:                                op.GrantTypes(s.Provider()),
 		SubjectTypesSupported:                              op.SubjectTypes(s.Provider()),
-		IDTokenSigningAlgValuesSupported:                   supportedSigningAlgs(ctx),
+		IDTokenSigningAlgValuesSupported:                   supportedSigningAlgs(),
 		RequestObjectSigningAlgValuesSupported:             op.RequestObjectSigAlgorithms(s.Provider()),
 		TokenEndpointAuthMethodsSupported:                  op.AuthMethodsTokenEndpoint(s.Provider()),
 		TokenEndpointAuthSigningAlgValuesSupported:         op.TokenSigAlgorithms(s.Provider()),