add support for typespec-ts-mode #5722

Job	Run time
test (ubuntu-latest, 27.2, false)	2m 14s
test (ubuntu-latest, 28.2, false)	2m 45s
test (ubuntu-latest, 29.4, false)	3m 44s
test (macos-latest, 28.2, false)	4m 31s
test (macos-latest, 29.4, false)	5m 5s
test (windows-latest, 27.2, false)	4m 53s
test (windows-latest, 28.2, false)	4m 37s
test (windows-latest, 29.4, false)	5m 51s
test (ubuntu-latest, snapshot, true)	2m 0s
test (macos-latest, snapshot, true)	2m 14s
test (windows-latest, snapshot, true)	2m 11s
	40m 5s

Provide feedback