Add "count" (badge) to toolbar item

[stropitek]

It adds a small colored "pill" on the corner of the button with the count displayed.

We expect an integer to be passed and I think you can adapt the font size based on if there is 1, 2, or more digits in the number.

Example in NMRium:

API suggestion:

// text color is always white
<Toolbar.Item count={3} countBackgroundColor="red" />

[wadjih-bencheikh18]

I like this style, WDYT?

And on hover

I used Tag component https://blueprintjs.com/docs/#core/components/tag

[stropitek]

SGTM, see PR comments