Frontend notification improvements

[kkovaletp]

Fixes #924.

Auto-calculate the container's height (up to 5 lines); wrap text inside the container and show a vertical scrollbar if needed; set a different color for the background of errors and success messages.

This is how it looks now with the fix on Mac in Firefox:

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 24.97%. Comparing base (4133694) to head (b463118).
Report is 6 commits behind head on master.

❗ Current head b463118 differs from pull request most recent head 0713c97

Please upload reports for the commit 0713c97 to get more accurate results.

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #965       +/-   ##
===========================================
- Coverage   56.43%   24.97%   -31.46%     
===========================================
  Files         196       96      -100     
  Lines       15601     4408    -11193     
  Branches      558        0      -558     
===========================================
- Hits         8804     1101     -7703     
+ Misses       6543     3053     -3490     
  Partials      254      254               

Flag	Coverage Δ
api	24.97% <ø> (+0.03%)	⬆️
ui	?

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[kkovaletp]

I've tried to write the unit test to cover my changes and the messages component in general, but stuck with failed tests and don't know how to fix the issue((
So, I'd appreciate your help if you know what is the root cause of the failure and how to fix it)