[5.3] [Events] Use event classes for Content plugins

[Fedik]

Summary of Changes

Update content plugins to use SubscriberInterface and event classes.

Testing Instructions

Check following content plugins should work as before:

confirmconsent
contact
emailcloak
fields
finder
joomla
loadmodule
pagebreak
pagenavigation
vote

Actual result BEFORE applying this Pull Request

Works

Expected result AFTER applying this Pull Request

Works

Link to documentations

Please select:

• Documentation link for docs.joomla.org: https://docs.joomla.org/Plugin/Events#Content
• No documentation changes for docs.joomla.org needed
• Pull Request link for manual.joomla.org: New Event classes Manual#177
• No documentation changes for manual.joomla.org needed

References:

• [5.0][Events] Content event classes #41226

[richard67]

Drone failure is not related to this PR.

[HLeithner]

This pull request has been automatically rebased to 5.3-dev.

[laoneo]

Can you fix the conflicts here?

[laoneo]

Thanks!