Add XLIFF formatting check and fixer

[oliverklee]

Story

As a developer, I want automation for having nicely formatted XLIFF files and for checking that, because I don't want to do these things manually.

Acceptance criteria

• We have a runTests.sh command for checking the formatting of XLIFF files.
• The command is run when the command for running all static checks is run.
• This check is run in our CI pipeline.
• We have a command in runTests.sh to fix the formatting of all XLIFF files.
• The command is run when the command for fixing everything is run.

Additional information

Core change