[backend] Avoid raising stack trace instead of returning a 404

[Dimfacion]

Proposed changes

• Instead of raising IllegalStateException or the generic NoSuchElementException, we're raising a custom defined Exception to keep the hand on where it is raised
• Adding a global exception handler to take care of the new exception and return a proper 404. The handler could be extended to add more intel when an exception is raised.

Related issues

• issue Avoid raising stack trace when entity is not found, just returning 404 #867

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality
• I wrote test cases for the relevant uses case
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality

Further comments

[codecov]

Codecov Report

Attention: Patch coverage is 7.18232% with 168 lines in your changes are missing coverage. Please review.

Project coverage is 27.31%. Comparing base (cedad5f) to head (e5976fc).
Report is 3 commits behind head on master.

Files	Patch %	Lines
...ain/java/io/openbas/rest/exercise/ExerciseApi.java	0.00%	34 Missing ⚠️
...rc/main/java/io/openbas/rest/inject/InjectApi.java	17.39%	19 Missing ⚠️
.../main/java/io/openbas/rest/channel/ChannelApi.java	25.00%	12 Missing ⚠️
...ain/java/io/openbas/rest/document/DocumentApi.java	0.00%	12 Missing ⚠️
.../main/java/io/openbas/rest/lessons/LessonsApi.java	0.00%	9 Missing ⚠️
.../src/main/java/io/openbas/rest/group/GroupApi.java	0.00%	8 Missing ⚠️
...n/java/io/openbas/rest/objective/ObjectiveApi.java	0.00%	8 Missing ⚠️
...pi/src/main/java/io/openbas/rest/team/TeamApi.java	0.00%	6 Missing ⚠️
...-api/src/main/java/io/openbas/rest/user/MeApi.java	0.00%	6 Missing ⚠️
...nbas/rest/lessons_template/LessonsTemplateApi.java	0.00%	5 Missing ⚠️
... and 22 more

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #885      +/-   ##
============================================
- Coverage     27.31%   27.31%   -0.01%     
- Complexity      917      919       +2     
============================================
  Files           410      412       +2     
  Lines          9280     9288       +8     
  Branches        431      431              
============================================
+ Hits           2535     2537       +2     
- Misses         6685     6691       +6     
  Partials         60       60              

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[RomuDeuxfois]

We need to rethink the management of 404 on the front side.

The user has an infinite loader when the entity does not exist right now, we need to display a 404 error message.