Bug 34307: Update plugin template to match master conventions

Bug 34307: Update plugin template to match master conventions

This change uses WRAPPER to build the breadcrumbs and
updates the plugin template to follow some other master conventions
like differentiating between Administration and Tools for plugins.

Test plan:
0. Apply patch
1. Upload koha-plugin-test-wrapper
2. Enable the plugin
3. Click "Actions" and click "Run tool"
4. Note how the plugin page looks like a perfect Koha Tools page
5. Note that the plugin only contains 6 lines of template code
to achieve this effect

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>