[NEW] Unify unread and mentions badge

[karlprieb]

@RocketChat/core

[ggazzo]

don't do that =/

is the number 1 relative to quantity of mentions? or just mentions|unread? ugly and confuse =/

[marceloschmidt]

Why not use what we had before: filled box or transparent background?

[engelgabriel]

The current way takes far too much space.

We can move to the old way (filled box or transparent background) but this PR is already an improvement.

@rodrigok please merge this and we can make another PR with the final version.

[ggazzo]

This situation is just on the hover. I dont think this "small/confuse" is better. But...

[engelgabriel]

@ggazzo you can do the PR for the old "filled box or transparent background" if your are so disappointed 😉