feat(api): add OIDC session service (#6157)

This PR starts the OIDC implementation for the API V2 including the Implicit and Code Flow.


Co-authored-by: Livio Spring <livio.a@gmail.com>
Co-authored-by: Tim Möhlmann <tim+github@zitadel.com>
Co-authored-by: Stefan Benz <46600784+stebenz@users.noreply.github.com>

build/zitadel/generate-grpc.sh

@@ -108,4 +108,16 @@ protoc \
   --validate_out=lang=go:${GOPATH}/src \
   ${PROTO_PATH}/settings/v2alpha/settings_service.proto
 
+protoc \
+  -I=/proto/include \
+  --grpc-gateway_out ${GOPATH}/src \
+  --grpc-gateway_opt logtostderr=true \
+  --grpc-gateway_opt allow_delete_body=true \
+  --openapiv2_out ${OPENAPI_PATH} \
+  --openapiv2_opt logtostderr=true \
+  --openapiv2_opt allow_delete_body=true \
+  --zitadel_out=${GOPATH}/src \
+  --validate_out=lang=go:${GOPATH}/src \
+  ${PROTO_PATH}/oidc/v2alpha/oidc_service.proto
+
 echo "done generating grpc"