Fix excessive allocations in EmbeddedResourceFileLoader #3244

Job	Run time
Build published projects without warnings (Release)	2m 28s
JS unit tests	1m 0s
.NET unit tests (ubuntu-latest)	2m 41s
Build all projects without errors	9m 2s
.NET unit tests (windows-2022)	11m 37s
Build published projects without warnings (Debug)	2m 24s
UI tests (chrome, ubuntu-latest, Production, Default)	15m 32s
.NET unit tests (macOS-latest)	3m 14s
UI tests (chrome, windows-2022, Development, Default)	25m 7s
UI tests (firefox, ubuntu-latest, Development, Default)	19m 46s
UI tests (firefox, ubuntu-latest, Production, Default)	17m 54s
UI tests (firefox, ubuntu-latest, Development, ExperimentalFeaturesTests)	18m 56s
UI tests (chrome, ubuntu-latest, Production, ExperimentalFeaturesTests)	15m 57s
	2h 25m 38s

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