First version with a new translation component

[joelit]

Reasons for creating this PR

Link to relevant issue(s), if any

• Closes Upgrade Skosmos to a new translation component #1247

Description of the changes in this PR

• Implementation of a new 'trans' filter for twig sing symfony/twig-bundle and symfony/translation
• Getting rid of the old twig-gettext-extractor
• Getting rid of the .mo files

Known problems or uncertainties in this PR

• Composer.json might have unnecessary dependencies
• Translation component should get the language parameter
• Unit tests need rewriting / getting rid of the old set-up

Checklist

• phpUnit tests pass locally with my changes
• I have added tests that show that the new code works, or tests are not relevant for this PR (e.g. only HTML/CSS changes)
• The PR doesn't reduce accessibility of the front-end code (e.g. tab focus, scaling to different resolutions, use of .sr-only class, color contrast)
• The PR doesn't introduce unintended code changes (e.g. empty lines or useless reindentation)

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[Vainonen]

This draft PR is continued in another PR #1466.