[TypeScript] Add methods for BufferedTokenStream #1038

Job	Run time
cpp-lib-build (macos-11, clang, ON)	10m 59s
cpp-lib-build (macos-11, clang, OFF)	10m 48s
build (macos-11, tool)	2m 3s
cpp-lib-build (macos-11, gcc, ON)	8m 15s
build (macos-11, cpp)	37m 13s
build (macos-11, csharp)	10m 9s
cpp-lib-build (macos-11, gcc, OFF)	8m 31s
build (macos-11, dart)	5m 51s
cpp-lib-build (ubuntu-20.04, clang, ON)	3m 39s
build (macos-11, go)	4m 56s
cpp-lib-build (ubuntu-20.04, clang, OFF)	3m 24s
build (macos-11, java)	2m 5s
cpp-lib-build (ubuntu-20.04, gcc, ON)	3m 25s
build (macos-11, javascript)	2m 40s
cpp-lib-build (ubuntu-20.04, gcc, OFF)	3m 22s
build (macos-11, typescript)	20m 25s
cpp-lib-build (windows-2022, clang, ON)	8m 11s
build (macos-11, php)	26s
cpp-lib-build (windows-2022, clang, OFF)	6m 5s
build (macos-11, python3)	2m 12s
cpp-lib-build (windows-2022, cl)	4m 48s
build (ubuntu-20.04, tool)	1m 0s
build (ubuntu-20.04, cpp)	17m 3s
build (ubuntu-20.04, csharp)	5m 4s
build (ubuntu-20.04, dart)	3m 33s
build (ubuntu-20.04, go)	2m 16s
build (ubuntu-20.04, java)	1m 11s
build (ubuntu-20.04, javascript)	1m 35s
build (ubuntu-20.04, typescript)	9m 58s
build (ubuntu-20.04, php)	1m 41s
build (ubuntu-20.04, python3)	1m 15s
build (windows-2022, tool)	1m 35s
build (windows-2022, cpp)	21m 50s
build (windows-2022, csharp)	11m 59s
build (windows-2022, dart)	4m 24s
build (windows-2022, go)	5m 48s
build (windows-2022, java)	1m 50s
build (windows-2022, javascript)	3m 23s
build (windows-2022, typescript)	26m 19s
build (windows-2022, php)	2m 39s
build (windows-2022, python3)	2m 59s
	4h 46m 49s

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