SGR 0 doesn't work correctly when combined with meta attributes

[j4james]

Environment

Windows build number: Version 10.0.18362.657
Windows Terminal version (if applicable): Commit ea1bb2e

Steps to reproduce

From a bash shell in conhost, execute the following command:

printf "\e[0;7mReverse\e[0;4mUnderline\e[m\n"

Expected behavior

It should display the first word with reversed video, and the second word underlined.

For example, here's what it looks like in mintty:

Actual behavior

The SGR 0 in the second sequence doesn't take effect, so the second word is both underlined and reversed.

[j4james]

I should mention that I'm currently experimenting with a refactor of the SGR code, based on a discussion we had in PR #3160 (comment). That refactoring actually fixes this bug (which is how I discovered it in the first place), but it's still a work in progress, and may be in that state for a while. However, if there is an urgent need for this to be fixed I can probably put together a simpler PR targetting just this bug.

[DHowett-MSFT]

No need for a rush fix on this one. I'll yank the triage tag off (and leave it in 21H1). Thanks for being our VT champion!