init m2m client

[fcaps]

Huge PR, but most of it are automatic code-style fixes and the "relocation" of all backend files into src/backend.

closes #505
closes #507
closes #495
closes #488
relates and fixes some issies with #478
preparation for #445

Whats in it?

• The new m2m client
• leaderboard reactivated for normal users
• All "backend" files are moved to src/backend, this has the advantage of having a cleaner structure and simpler config for linters, webpack etc.
• Introducing AppKernel and retiring fafApp, this makes testing and understanding whats going on simpler and rubust
• Introducting ServiceContainer to reduce the clutter with config/functions/classes everywhere, reduce duplicated code and make testing soo much easier
• Fixing report player, this time i took my time to actually fix it
• Some minor fixes here and there

[codecov]

Codecov Report

Attention: 554 lines in your changes are missing coverage. Please review.

Comparison is base (29b71cb) 43.56% compared to head (d8435a3) 46.22%.
Report is 1 commits behind head on develop.

Files	Patch %	Lines
src/backend/routes/views/account/get/report.js	4.16%	46 Missing ⚠️
src/backend/routes/views/account/post/register.js	11.62%	38 Missing ⚠️
src/backend/routes/views/account/post/report.js	7.31%	38 Missing ⚠️
src/backend/routes/views/account/post/linkGog.js	13.88%	31 Missing ⚠️
...ackend/routes/views/account/post/changePassword.js	15.15%	28 Missing ⚠️
...c/backend/routes/views/account/get/connectSteam.js	10.34%	26 Missing ⚠️
src/backend/cron-jobs/wordpressCacheCrawler.js	16.66%	25 Missing ⚠️
src/backend/routes/views/account/post/activate.js	16.66%	25 Missing ⚠️
.../routes/views/account/post/confirmPasswordReset.js	16.66%	25 Missing ⚠️
src/backend/cron-jobs/leaderboardCacheCrawler.js	18.51%	22 Missing ⚠️
... and 30 more

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #504      +/-   ##
===========================================
+ Coverage    43.56%   46.22%   +2.66%     
===========================================
  Files           50       56       +6     
  Lines         1173     1205      +32     
  Branches       140      131       -9     
===========================================
+ Hits           511      557      +46     
+ Misses         648      634      -14     
  Partials        14       14              

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