[Swift] Adds new API to reduce memory copying within swift #6656

Job	Run time
Build Benchmarks (on Linux) (g++-13)	2m 48s
Build Windows C++ (11)	3m 26s
Build Android (on Linux)	3m 16s
Build Windows C++ (14)	4m 25s
Build Dart	1m 12s
Build Windows C++ (17)	3m 55s
Build .NET Windows	1m 48s
Build Windows C++ (20)	5m 36s
Build .NET Windows (-p:UnsafeByteBuffer=true)	1m 38s
Check Generated Code (g++-13)	1m 1s
Check Generated Code on Windows	3m 41s
Build Windows C++ (23)	5m 30s
Check Generated Code (clang++-18)	1m 22s
Build Go	1m 17s
Build Java	22s
Build Kotlin Linux	2m 56s
Build Kotlin MacOS	8m 15s
Build Linux (g++-13)	1m 48s
Build Linux with -DFLATBUFFERS_NO_FILE_TESTS	2m 5s
Build Linux C++ (11, g++-13)	1m 45s
Build Linux (clang++-18)	2m 9s
Build Linux with out-of-source build location	1m 11s
Build Linux C++ (11, clang++-18)	2m 0s
Build Mac (for Intel)	2m 44s
Build Linux C++ (14, g++-13)	1m 43s
Build Mac (universal build)	3m 48s
Build Nim	1m 9s
Build Linux C++ (14, clang++-18)	2m 7s
Build PHP	1m 0s
Build Linux C++ (17, g++-13)	1m 57s
Build Python	56s
Build Rust Linux	1m 53s
Build Linux C++ (17, clang++-18)	2m 13s
Build Linux C++ (20, g++-13)	2m 8s
Build Rust Windows	1m 26s
Build Swift (5.8)	1m 5s
Build Swift Wasm	2m 43s
Build Linux C++ (20, clang++-18)	2m 34s
Build Swift (5.9)	1m 18s
Build Swift (5.10)	1m 16s
Build TS	1m 22s
Build Linux C++ (23, g++-13)	2m 8s
Build Windows 2019	4m 20s
release-digests	0s
provenance	0s
	1h 43m 16s

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