feat(Toolbar): add component

[miroslavstastny]

Basic Toolbar implementation

Toolbar currently supports three kinds of items:

• ToolbarItem - the icon button in the toolbar,
• ToolbarDivider - visual separator between items,
• ToolbarRadiogroup - logical grouping of ToolbarItem (can also contain ToolbarDivider).

See https://www.w3.org/TR/wai-aria-practices/examples/toolbar/toolbar.html for details on accessibility.

• unit tests
• docsite example
• teams, teamsDark, teamsHighContrast themes
• changelog

To be handled in separate tasks:

• menu - Toolbar - menu #1411
• popup - Toolbar - popup #1410
• accessibility - Toolbar - accessibility behavior #1413
• overflow menu - Toolbar - Overflow menu #1409

[kuzhelov]

just the thought unrelated to this PR - really think that we need to introduce siteVariables's types for Teams theme - otherwise it might become to be pretty complicated story to maintain all this, especially given that name of the variable is not fixed on the client side

[codecov]

Codecov Report

Merging #1408 into master will decrease coverage by 0.08%.
The diff coverage is 60.93%.

@@            Coverage Diff             @@
##           master    #1408      +/-   ##
==========================================
- Coverage   73.57%   73.49%   -0.09%     
==========================================
  Files         787      797      +10     
  Lines        5885     5949      +64     
  Branches     1734     1746      +12     
==========================================
+ Hits         4330     4372      +42     
- Misses       1549     1571      +22     
  Partials        6        6

Impacted Files	Coverage Δ
packages/react/src/index.ts	100% <ø> (ø)	⬆️
packages/react/src/components/Menu/MenuItem.tsx	34.04% <ø> (+3.19%)	⬆️
...gh-contrast/components/Toolbar/toolbarVariables.ts	0% <0%> (ø)
.../teams-dark/components/Toolbar/toolbarVariables.ts	0% <0%> (ø)
...hemes/teams/components/Toolbar/toolbarVariables.ts	0% <0%> (ø)
...es/react/src/components/Toolbar/ToolbarDivider.tsx	100% <100%> (ø)
...emes/teams/components/Toolbar/toolbarItemStyles.ts	14.28% <14.28%> (ø)
...rc/themes/base/components/Toolbar/toolbarStyles.ts	50% <50%> (ø)
...s/teams/components/Toolbar/toolbarDividerStyles.ts	50% <50%> (ø)
packages/react/src/components/Toolbar/Toolbar.tsx	52.94% <52.94%> (ø)
... and 13 more

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[codecov]

Codecov Report

Merging #1408 into master will decrease coverage by 0.21%.
The diff coverage is 52.63%.

@@            Coverage Diff             @@
##           master    #1408      +/-   ##
==========================================
- Coverage   73.49%   73.27%   -0.22%     
==========================================
  Files         793      802       +9     
  Lines        5949     6025      +76     
  Branches     1754     1775      +21     
==========================================
+ Hits         4372     4415      +43     
- Misses       1571     1604      +33     
  Partials        6        6

Impacted Files	Coverage Δ
packages/react/src/index.ts	100% <ø> (ø)	⬆️
.../src/themes/teams/components/Menu/menuVariables.ts	33.33% <ø> (ø)	⬆️
packages/react/src/components/Menu/MenuItem.tsx	34.04% <ø> (+3.19%)	⬆️
...gh-contrast/components/Toolbar/toolbarVariables.ts	0% <0%> (ø)
...es/react/src/components/Toolbar/ToolbarDivider.tsx	100% <100%> (ø)
...s/teams/components/Toolbar/toolbarDividerStyles.ts	20% <20%> (ø)
...rc/themes/base/components/Toolbar/toolbarStyles.ts	50% <50%> (ø)
...hemes/teams/components/Toolbar/toolbarVariables.ts	50% <50%> (ø)
packages/react/src/components/Toolbar/Toolbar.tsx	52.94% <52.94%> (ø)
...emes/teams/components/Toolbar/toolbarItemStyles.ts	6.25% <6.25%> (ø)
... and 12 more

---

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[mnajdova]

nit: we may want to extend the color scheme, and use the foregroundDisabled1 for the foregroundDisabled, so it would be more user friendly, but then it may raise a problem because the user will think this one is acttually the foregroundDisabled from the color scheme... Let's just think about this and decide together whether we want that.