Update TS codegen - change `getFullyQualifiedName` return type from string to string literal #6850

Job	Run time
Build Benchmarks (on Linux) (g++-13)	2m 51s
Build Android (on Linux)	3m 28s
Bazel	1m 42s
Build Windows C++ (11)	3m 15s
Build Dart	1m 10s
Build Windows C++ (14)	3m 42s
Check Generated Code (g++-13)	1m 3s
Build Windows C++ (17)	4m 32s
Check Generated Code (clang++-18)	1m 12s
Build .NET Windows	1m 28s
Check Generated Code on Windows	3m 50s
Build Windows C++ (20)	5m 38s
Build .NET Windows (-p:UnsafeByteBuffer=true)	1m 57s
Build Windows C++ (23)	5m 44s
Build Java	14s
Build Go	1m 20s
Build Kotlin Linux	3m 23s
Build Kotlin MacOS	3m 58s
Build Linux (g++-13)	1m 47s
Build Linux C++ (11, g++-13)	1m 42s
Build Linux (clang++-18)	1m 58s
Build Linux with -DFLATBUFFERS_NO_FILE_TESTS	1m 58s
Build Linux with out-of-source build location	1m 18s
Build Linux C++ (11, clang++-18)	2m 2s
Build Linux C++ (14, g++-13)	1m 44s
Build Mac (for Intel)	1m 34s
Build Mac (universal build)	1m 37s
Build Linux C++ (14, clang++-18)	1m 57s
Build Nim	1m 8s
Build Linux C++ (17, g++-13)	1m 57s
Build PHP	57s
Build Linux C++ (17, clang++-18)	2m 11s
Build Python	59s
Build Linux C++ (20, g++-13)	2m 5s
Build Rust Linux	2m 2s
Build Rust Windows	1m 45s
Build Linux C++ (20, clang++-18)	2m 26s
Build Swift (5.8)	2m 5s
Build Linux C++ (23, g++-13)	2m 7s
Build Swift (5.9)	2m 20s
Build Swift Wasm	3m 30s
Build TS	1m 16s
Build Swift (5.10)	2m 13s
Build Windows 2019	4m 46s
release-digests	0s
provenance	0s
	1h 41m 51s

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