Add wrapper scripts for common translation operations

[osma]

Reasons for creating this PR

While reviewing the documentation for translations in Skosmos 3, it became apparent that the current commands for common operations such as extract, pull and push are quite unwieldy. This PR adds wrapper shell scripts that make them much easier.

Link to relevant issue(s), if any

• part of Epic: Translation Infrastructure #1712

Description of the changes in this PR

• add .env.local into .gitignore (commonly used to hold Lokalise API keys that shouldn't be committed to version control)
• add the scripts extract-translations, push-translations and pull-translations

Known problems or uncertainties in this PR

The documentation needs to be updated as well so it encourages using these scripts.

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)

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[UnniKohonen]

Tested the scripts and they seem to be working as expected. LGTM!

[osma]

I changed the documentation to use these scripts instead of the full commands.