Bug 31503: (follow-up) Add 'feature_enabled' to Koha::Plugins

Bug 31503: (follow-up) Add 'feature_enabled' to Koha::Plugins

This patch adds a 'feature_enabled' accessor to the Koha::Plugins class.
Passing the plugin method name for the plugin feature you're looking for
will return a boolean denoting whether any enabled plugins carry said
method.

Included in the patch is an addition to the TT KohaPlugins plugin to
enable quick access to this function.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
[EDIT] Tidied t/db_dependent/Koha/Plugins/Plugins.t
[EDIT] Tidied Koha/Template/Plugin/KohaPlugins.pm

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>