Add crowdin.yml configuration file 🗺️

[darcywong00]

For #384

This adds a crowdin configuration file (supports Crowdin CLI 4.0+).
One limitation is when downloading translated strings, the escaped parameters (e.g. %1\$) get downloaded as %1\\$ so there's an extra step added to init-container.sh to fix the escaping.

The languages_mapping section uses canonical locales so de files in Crowdin don't get downloaded to de-DE.php

  - source: /_includes/locale/strings/keyboards/en.php
    dest: /keyboards/keyboards/en.php
    translation: /_includes/locale/strings/keyboards/%locale%.php
    languages_mapping:
      locale:
        # Canonical locales as needed
        es-ES: es
        de: de
        fr: fr
        km: km

Test-bot: skip

[keymanapp-test-bot]

User Test Results

Test specification and instructions

User tests are not required