Fix API creating tag duplicates

[patrykgruszka]

Q	A
Branch?	"features"
Bug fix?	yes
New feature?	no
Deprecations?	no
BC breaks?	no
Automated tests included?	yes
Related user documentation PR URL
Related developer documentation PR URL
Issue(s) addressed

Description:

Creating new tags through API with special characters (e.q ", ') or whitespace in the beginning/end of the string causes duplicates.

Relates to #6057 #7741

Steps to test this PR:

1. Apply this PR
2. Create new tag with API POST /api/tags/new with data:

{
    "tag": "hello'world"
}

3. Note the ID and repeat previous request with same data
4. Only one tag should be created, second call should return the same tag ID

[codecov]

Codecov Report

Merging #10270 (9fed0e0) into 4.0 (4cb5404) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##                4.0   #10270      +/-   ##
============================================
+ Coverage     43.29%   43.31%   +0.02%     
+ Complexity    34533    34532       -1     
============================================
  Files          2062     2062              
  Lines        115624   115647      +23     
============================================
+ Hits          50060    50096      +36     
+ Misses        65564    65551      -13     

Impacted Files	Coverage Δ
app/bundles/LeadBundle/Entity/Tag.php	100.00% <100.00%> (ø)
app/bundles/LeadBundle/Entity/TagRepository.php	35.29% <100.00%> (-1.25%)	⬇️
...les/LeadBundle/Controller/Api/TagApiController.php	100.00% <0.00%> (+9.09%)	⬆️
...les/CoreBundle/EventListener/ExceptionListener.php	44.44% <0.00%> (+33.33%)	⬆️
...dles/CoreBundle/Controller/ExceptionController.php	41.37% <0.00%> (+41.37%)	⬆️

[kuzmany]

Looks good 👍
Unit test included 👍
Works for me 👍

[mabumusa1]

The code looks good, there are unit tests.

I think this PR is good to be merged

[dennisameling]

The reason for the decreased code coverage is that, while a bunch of tests were added for the TagApiControllerFunctionalTest, it doesn't increase the code coverage as these things are routed through the CommonApiController, which is the same for many API endpoints and not specific to the TagApi. There is some specific error handling in TagApiController which wasn't covered by a test yet, so I just added one for that.

Merging now 👍🏼