Overhauled and improved translation extraction and handling

[Guite]

Q	A
Bug fix?	yes
New feature?	yes
BC breaks?	no
Deprecations?	no
Fixed tickets	#4012
Refs tickets	#2425, #4057
License	MIT
Changelog updated	yes

Description

This PR basically includes the following amendments:

• Remove JMSTranslationBundle entirely
• Install and enable php-translation/symfony-bundle instead
• Configure it's functionality and create two configurations (one for core and one for extensions)
• Add a new GitHub actions workflow for running the extractor every 2 days and adding missing translations as a pull request
• Add annotations (@Ignore and @Translate) where needed
• Remove more unrequired translator calls in form types
• Move some remaining form creations from controllers into form types
• Remove unrequired translator calls in flashes
• Add docs for translator and extractor handling (will be finished in Unify and update translation docs #4057)
• Utilise the "Edit in Place" functionality
• Utilise the "WebUI" functionality
• Change the way we use translation domains (not equal to the bundle name anymore, but a context for translators, like for example mail, messages, navigation, validators and admin)
• Extend LocaleApi to support lists without and with regions (e.g. de_DE)
• Centralise locale-related parameters and reuse for different bundles
• Extend LocaleApi to reflect auto-discovery of new/removed locales in configuration (using new LocaleConfigHelper)
• Implement dynamic configuration handling for translation settings (required e.g. for web ui) (using new TranslationConfigHelper)
• Add missing extractor for form type alerts
• Add missing extractor for form type input groups
• Add missing extractors for KnpMenuBundle
• Add missing extractor for JMSI18nRoutingBundle

[craigh]

please add extraction to travis job when this is ready

[Guite]

please add extraction to travis job when this is ready

I've already setup an independent Github workflow: https://github.com/zikula/core/blob/translation/.github/workflows/update-translations.yml
This is going to create pull requests for new/missing translations.