Better API for activity filters, settings and providers + Rich Object support

[nickvergessen]

• Activity PR: Activity filters, settings and providers update activity#70

Changes

• Split the huge and non-understandable IExtension into three interfaces: IFilter, ISetting and IProvider
• Allow to register filters via info.xml
• Allow to register settings via info.xml
• Allow to register provideres via info.xml
• Adds support for Rich Object Strings ( Nextcloud Rich Object Strings #1706 ) to activities fixing the huge topic in the OC issues, so the clients can finally link file names and so on as well

Compatibility

• Translations (Handled by activity app with a provider)
• Old files/usernames in strings (Handled by activity app with a provider)
• Settings (Handled by activity manager)
• Filters (Handled by activity manager)

Breaking

• Grouping of similar subsequent message (Todo for a second PR)
• Icons of filters and events (URL vs. CSS class)
• Direct SQL manipulation for filters (only usecase was favorites - functionality still available)

[LukasReschke]

👍 Awesome work! 🚀 👯 🍻

[rullzer]

There was by no means a gun to my head.
But 👍