Rely on the plugin_manual mechanism in Foreman

[ekohl]

This combines https://github.com/theforeman/foreman_remote_execution/pull/819 and https://github.com/theforeman/foreman/pull/9756.

[ekohl]

Rebased to resolve a merge conflict, now ready for review. Still includes #819.

[ekohl]

Rebased now that 26b5c4ae1f2ac9e3cc962352b38bd93def8d3a63 was merged. It's a bit inconsistent that some parts weren't updated to the new docs.

[ekohl]

There are 2 places where it's used:

$ rg documentation_button_rex
app/views/job_templates/index.html.erb
5:<% title_actions(documentation_button_rex('3.1JobTemplates'),

app/helpers/remote_execution_helper.rb
57:      documentation_button_rex('3.2ExecutingaJob'),
211:  def documentation_button_rex(section = '')

Given 26b5c4ae1f2ac9e3cc962352b38bd93def8d3a63 changed one link to the new documentation, should we align on the new docs instead?

[adamruzicka]

should we align on the new docs instead?

That would be ideal

[ekohl]

I don't think I'll have time to find out which sections it should link to so I'd prefer to hand it over then.