[Swift] Adds new API to reduce memory copying within swift #6673

Job	Run time
Build Android (on Linux)	3m 21s
Build Windows C++ (11)	4m 14s
Check Generated Code (g++-13)	1m 2s
Build Windows C++ (14)	4m 14s
Build .NET Windows	1m 53s
Check Generated Code (clang++-18)	1m 15s
Build Windows C++ (17)	4m 34s
Build .NET Windows (-p:UnsafeByteBuffer=true)	1m 41s
Build Windows C++ (20)	5m 34s
Check Generated Code on Windows	4m 9s
Build Windows C++ (23)	5m 33s
Build Linux C++ (11, g++-13)	1m 44s
Build Linux with -DFLATBUFFERS_NO_FILE_TESTS	2m 0s
Build Linux C++ (11, clang++-18)	2m 0s
Build Linux with out-of-source build location	1m 17s
Build Linux C++ (14, g++-13)	1m 46s
Build Mac (for Intel)	1m 56s
Build Mac (universal build)	1m 32s
Build Windows 2019	4m 4s
Build Linux C++ (14, clang++-18)	1m 59s
Build Benchmarks (on Linux) (g++-13)	2m 46s
Build Linux C++ (17, g++-13)	1m 55s
Build Linux C++ (17, clang++-18)	2m 9s
Build Go	1m 18s
Build Linux C++ (20, g++-13)	2m 5s
Build Java	24s
Build Linux C++ (20, clang++-18)	2m 26s
Build Kotlin Linux	6s
Build Kotlin MacOS	5m 20s
Build Linux C++ (23, g++-13)	2m 8s
Build Linux (g++-13)	1m 48s
Build PHP	57s
Build Linux (clang++-18)	2m 7s
Build Python	54s
Build Rust Linux	2m 0s
Build Rust Windows	1m 27s
Build Swift (5.8)	2m 0s
Build Swift (5.9)	2m 17s
Build Swift Wasm	3m 16s
Build Swift (5.10)	2m 20s
Build Dart	1m 13s
Build Nim	1m 8s
Build TS	1m 19s
release-digests	0s
provenance	0s
	1h 39m 11s

Provide feedback