feat(Icon): add outline prop

[layershifter]

Fixes #793.

BREAKING CHANGES

This PR removes the iconVariables.outline variable and introduces the outline prop.

Before

<Icon name="calendar" variables={{ outline: true }} />

After

<Icon name="calendar" outline />

[codecov]

Codecov Report

Merging #1002 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master    #1002   +/-   ##
=======================================
  Coverage   81.15%   81.15%           
=======================================
  Files         673      673           
  Lines        8653     8653           
  Branches     1528     1463   -65     
=======================================
  Hits         7022     7022           
  Misses       1616     1616           
  Partials       15       15

Impacted Files	Coverage Δ
packages/react/src/components/Icon/Icon.tsx	83.33% <ø> (ø)	⬆️
.../src/themes/teams/components/Icon/iconVariables.ts	100% <ø> (ø)	⬆️
...act/src/themes/teams/components/Icon/iconStyles.ts	22.58% <0%> (ø)	⬆️

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[mnajdova]

I don't like that here we are kind a suggesting that the outline is part of the name :\ Not related to your changes, but would rather see something like <Icon name=${name.replace(processedIconsNamePrefix, '')} outline /> or some object {name: ${name.replace(processedIconsNamePrefix, '')}, outline: true}, because I was asked multiple times by people about what the name like outline for example for the Icon's doesn't work. It is not obvious that the outline is something else...

[layershifter]

Added copy 😺

[mnajdova]

LGTM

[kuzhelov]

👍