Bug 21905: Plugin hook intranet_catalog_biblio_enhancements_toolbar_button incorrectl...

Bug 21905: Plugin hook intranet_catalog_biblio_enhancements_toolbar_button incorrectly filtered

The new plugin hook intranet_catalog_biblio_enhancements_toolbar_button is rendered useless due to the outputted html being escaped using the html filter. It should be using the raw filter instead.

Test Plan:
1) Enable plugins
2) Download and install the latest version of the Kitchen Sink plugin
   https://github.com/bywatersolutions/koha-plugin-kitchen-sink/releases/download/v2.1.21/koha-plugin-kitchen-sink-v2.1.21.kpz
3) Browse to catalogue/detail.pl for a record
4) Note you see the raw html of the plugin output in the toolbar
5) Apply this patch
6) Restart all the things
7) Reload the page
8) Note the html is now correctly rendered as a button

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>