Help packaging MediaEditor installPhase (Existing PR)

This PR compiles, but I’m not sure how to implement the installPhase. Due to the way theirCMakeLists.txt is composed, it seems to ignore most cmakeFlags as set() is hardcoded multiple times.

Currently, it just seems to spit .so files and the mec binary out in the source directory, and the mec program contains illegal references to /build.

media-editor> lrwxrwxrwx  1 nixbld nixbld   20 Aug 28 14:39 libBluePrintSDK.so -> libBluePrintSDK.so.1
media-editor> lrwxrwxrwx  1 nixbld nixbld   26 Aug 28 14:39 libBluePrintSDK.so.1 -> libBluePrintSDK.so.1.18.10
media-editor> -rwxr-xr-x  1 nixbld nixbld 1.3M Aug 28 14:39 libBluePrintSDK.so.1.18.10
media-editor> lrwxrwxrwx  1 nixbld nixbld   17 Aug 28 14:39 libMediaCore.so -> libMediaCore.so.1
media-editor> lrwxrwxrwx  1 nixbld nixbld   22 Aug 28 14:39 libMediaCore.so.1 -> libMediaCore.so.1.9.14
media-editor> -rwxr-xr-x  1 nixbld nixbld 2.3M Aug 28 14:39 libMediaCore.so.1.9.14
media-editor> lrwxrwxrwx  1 nixbld nixbld   16 Aug 28 14:39 libVkShader.so -> libVkShader.so.1
media-editor> lrwxrwxrwx  1 nixbld nixbld   21 Aug 28 14:39 libVkShader.so.1 -> libVkShader.so.1.10.1
media-editor> -rwxr-xr-x  1 nixbld nixbld  11M Aug 28 14:39 libVkShader.so.1.10.1
media-editor> lrwxrwxrwx  1 nixbld nixbld   13 Aug 28 14:39 libimgui.so -> libimgui.so.1
media-editor> lrwxrwxrwx  1 nixbld nixbld   19 Aug 28 14:39 libimgui.so.1 -> libimgui.so.1.89.82
media-editor> -rwxr-xr-x  1 nixbld nixbld  19M Aug 28 14:39 libimgui.so.1.89.82
media-editor> -rwxr-xr-x  1 nixbld nixbld 1.5M Aug 28 14:40 mec
media-editor> -rwxr-xr-x  1 nixbld nixbld 108K Aug 28 14:39 media_player_test
media-editor> drwxr-xr-x  3 nixbld nixbld    3 Aug 28 14:39 plugin
media-editor> drwxr-xr-x  6 nixbld nixbld    6 Aug 28 14:39 plugins

This requires so much work that it is better to rewrite the installation logic using Cmake GID:

https://cmake.org/cmake/help/latest/module/GNUInstallDirs.html