[UR] Allow for extending enums #1622

Job	Run time
Build - Ubuntu (ubuntu-20.04, Debug, gcc, g++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=OFF)	6m 41s
Build - Ubuntu (ubuntu-20.04, Release, gcc, g++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=OFF)	5m 51s
Build - Ubuntu (ubuntu-22.04, Debug, gcc, g++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=OFF)	6m 19s
Build - Ubuntu (ubuntu-22.04, Release, gcc, g++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=OFF)	6m 2s
Build - Ubuntu (ubuntu-22.04, Release, clang, clang++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=OFF)	5m 17s
Build - Ubuntu (ubuntu-22.04, Release, gcc, g++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=ON)	7m 15s
Build - Ubuntu (ubuntu-22.04, Release, clang, clang++, -DVAL_USE_LIBBACKTRACE_BACKTRACE=ON)	8m 28s
Build - Ubuntu (ubuntu-20.04, Release, gcc-7, g++-7)	5m 30s
Build - Windows (windows-2019, Debug)	10m 18s
Build - Windows (windows-2019, Release)	11m 32s
Build - Windows (windows-2022, Debug)	11m 31s
Build - Windows (windows-2022, Release)	13m 24s
	1h 38m 8s

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