Fix duplicate extension commands autogen If a command exists in two or more extensions with different suffixes but does not exist in any core version, ensured that the command declaration is added to context only once. Bug: angleproject:414506477 Change-Id: I22e5290bd9b89da8fb8dc01647d29cf67d864b8d Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6519422 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>