Support ContentPlaceHolder inside CompositeControl templates (deferred master page composition) #3772

Job	Run time
Build published projects without warnings (Debug)	3m 26s
Build all projects without errors	6m 2s
.NET unit tests (ubuntu-latest)	6m 18s
Build published projects without warnings (Release)	3m 19s
.NET unit tests (macOS-latest)	3m 35s
.NET unit tests (windows-2022)	7m 54s
JS unit tests	58s
UI tests (firefox, ubuntu-latest, Development, Default, /test-basepath)	13m 26s
UI tests (chrome, ubuntu-latest, Production, Default)	14m 8s
UI tests (firefox, ubuntu-latest, Development, ExperimentalFeaturesTests)	15m 0s
UI tests (firefox, ubuntu-latest, Production, Default)	13m 19s
UI tests (chrome, windows-2022, Development, Default)	18m 27s
UI tests (chrome, ubuntu-latest, Production, ExperimentalFeaturesTests)	14m 2s
	1h 59m 54s

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