Add support for dot in sprintf format. #1747

Job	Run time
Build on windows-latest for repo global.json	16m 47s
Build on windows-latest for 6.0 stable	17m 57s
Build on windows-latest for 7.0 preview	18m 35s
Build on macos-latest for repo global.json	23m 36s
Build on macos-latest for 6.0 stable	24m 53s
Build on macos-latest for 7.0 preview	23m 38s
Build on ubuntu-latest for repo global.json	13m 40s
Build on ubuntu-latest for 6.0 stable	16m 6s
Build on ubuntu-latest for 7.0 preview	14m 35s
	2h 49m 47s

Provide feedback