Fix excessive allocations in EmbeddedResourceFileLoader #3236

Job	Run time
JS unit tests	1m 1s
Build published projects without warnings (Release)	5m 10s
Build all projects without errors	12m 30s
Build published projects without warnings (Debug)	2m 38s
.NET unit tests (ubuntu-latest)	2m 51s
UI tests (chrome, ubuntu-latest, Production, Default)	14m 42s
.NET unit tests (windows-2022)	8m 6s
UI tests (chrome, windows-2022, Development, Default)	26m 9s
.NET unit tests (macOS-latest)	6m 45s
UI tests (firefox, ubuntu-latest, Development, Default)	19m 20s
UI tests (firefox, ubuntu-latest, Production, Default)	18m 8s
UI tests (firefox, ubuntu-latest, Development, ExperimentalFeaturesTests)	20m 17s
UI tests (chrome, ubuntu-latest, Production, ExperimentalFeaturesTests)	16m 10s
	2h 33m 47s

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