[ACA-1957] Create Library - check existent site title by field

[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

❗ No coverage uploaded for pull request base (development@0b65ff4). Click here to learn what that means.
The diff coverage is 0%.

@@              Coverage Diff               @@
##             development     #765   +/-   ##
==============================================
  Coverage               ?   51.09%           
==============================================
  Files                  ?      106           
  Lines                  ?     2965           
  Branches               ?      593           
==============================================
  Hits                   ?     1515           
  Misses                 ?     1372           
  Partials               ?       78

Impacted Files	Coverage Δ
src/app/dialogs/library/library.dialog.ts	5.76% <0%> (ø)

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