fix(Alert): correctly handle RTL if shorthand API is used

[miroslavstastny]

Fixes #2017
Set dir="auto" on Alert only if Children API is used.
If shorthand API is used, content is wrapped by its own Text component, no need to set dir on parent container.

[codecov]

Codecov Report

Merging #2018 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master   #2018   +/-   ##
======================================
  Coverage    75.8%   75.8%           
======================================
  Files         160     160           
  Lines        5572    5572           
  Branches     1631    1614   -17     
======================================
  Hits         4224    4224           
  Misses       1334    1334           
  Partials       14      14

Impacted Files	Coverage Δ
packages/react/src/components/Alert/Alert.tsx	80% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f234425...dc0aa3d. Read the comment docs.