Bug 31339: Add staff wrapper template include for tool plugins

Bug 31339: Add staff wrapper template include for tool plugins

This change adds a template include which can be used as a
WRAPPER for tool plugins, which makes it easy to pages in tool
templates without having to copy and maintain a lot of template
boilerplate.

Test plan:
0. Apply patch and koha-plack --restart kohadev
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: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>