feat(Dialog): add headerAction slot

[mnajdova]

This PR adds a headerAction to the Dialog component. This button is text and iconOnly and is rendered after the header slot. I noticed that it is the first thing focused when the Dialog is opened (not sure if this is the behavior we want) @jurokapsiar @sophieH29 please share your thoughts on this. Also the focus indicator is not implemented for the textOnly variant for the button. I may add that as part of this PR.

[codecov]

Codecov Report

Merging #1617 into master will decrease coverage by 0.02%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #1617      +/-   ##
==========================================
- Coverage   71.48%   71.46%   -0.03%     
==========================================
  Files         845      845              
  Lines        6943     6945       +2     
  Branches     1980     1981       +1     
==========================================
  Hits         4963     4963              
- Misses       1974     1976       +2     
  Partials        6        6

Impacted Files	Coverage Δ
packages/react/src/components/Dialog/Dialog.tsx	31.57% <ø> (ø)	⬆️
.../themes/teams/components/Dialog/dialogVariables.ts	0% <ø> (ø)	⬆️
.../src/themes/base/components/Dialog/dialogStyles.ts	0% <ø> (ø)	⬆️
...src/themes/teams/components/Button/buttonStyles.ts	3.44% <0%> (-0.13%)	⬇️
...src/themes/teams/components/Dialog/dialogStyles.ts	0% <0%> (ø)	⬆️

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[jurokapsiar]

@sophieH29 let's discuss - we might do something like looking for the focusable in content first and then in the header actions if we did not find anything

@mnajdova yes, the focus indicator should be there - I will leave it up to you if you want to add it in this PR or if you want to create an issue - it probably also depends on if you have the red lines or not.

[mnajdova]

Added focus styles for the text button

[bmdalex]

one comment

[miroslavstastny]

We should add screener tests for open dialogs, popups, tooltips... (probably in a separate task)

[mnajdova]

We should add screener tests for open dialogs, popups, tooltips... (probably in a separate task)

@miroslavstastny I thought about the same thing, so I added steps for the Dialog - the new example and the example with the content... In a separate pr we can add more examples for the popups and tooltips.