Switch back to ts-loader

[patrys]

awesome-typescript-loader used to be the faster option but nowadays it seems not to be maintained any more.

Local performance benchmark:

Loader	Cold cache	Warm cache
ts-loader	35s	15s
awesome-typescript-loader	44s	23s

Pull Request Checklist

1. Privileged views and APIs are guarded by proper permission checks.
2. All visible strings are translated with proper context.
3. All data-formatting is locale-aware (dates, numbers, and so on).
4. Database queries are optimized and the number of queries is constant.
5. Database migration files are up to date.
6. The changes are tested.
7. The code is documented (docstrings, project documentation).
8. GraphQL schema and type definitions are up to date.
9. Changes are mentioned in the changelog.

[patrys]

@dominik-zeglen Please compare the execution time on your machine.

[codecov]

Codecov Report

Merging #3545 into fix-dependencies will not change coverage.
The diff coverage is n/a.

@@                Coverage Diff                @@
##           fix-dependencies    #3545   +/-   ##
=================================================
  Coverage             89.82%   89.82%           
=================================================
  Files                   250      250           
  Lines                 13194    13194           
  Branches               1333     1333           
=================================================
  Hits                  11852    11852           
  Misses                  930      930           
  Partials                412      412

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