refactor(semantic): simplify handling namespace stack #24619

Job	Run time
Build Linter Benchmark	2m 39s
Benchmark (lexer)	1m 27s
Benchmark (parser)	1m 48s
Benchmark (transformer)	2m 12s
Benchmark (isolated_declarations)	2m 14s
Benchmark (semantic)	1m 50s
Benchmark (minifier)	1m 56s
Benchmark (codegen)	2m 7s
Benchmark linter (0)	2m 58s
Benchmark linter (1)	1m 44s
Upload benchmarks	16s
	21m 11s

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