[ACA-1057] Upload - snack-bar error messages

[pionnegru]

PR Checklist

Please check if your PR fulfills the following requirements:

- [ ] The commit message follows our guidelines: https://github.com/Alfresco/alfresco-content-app/blob/master/CONTRIBUTING.md#commit
- [ ] Tests for the changes have been added (for bug fixes / features)
- [ ] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Application / Infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[ ] No

Other information

[codecov-io]

Codecov Report

Merging #837 into development will increase coverage by 0.51%.
The diff coverage is 100%.

@@               Coverage Diff               @@
##           development     #837      +/-   ##
===============================================
+ Coverage        62.84%   63.35%   +0.51%     
===============================================
  Files              113      113              
  Lines             3921     3927       +6     
  Branches           645      648       +3     
===============================================
+ Hits              2464     2488      +24     
+ Misses            1335     1317      -18     
  Partials           122      122

Impacted Files	Coverage Δ
src/app/app.component.ts	50% <100%> (+36.2%)	⬆️

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