bugfix: only provide taskgroup link if you can follow it.

[Dane-2pi]

Checklist

• I'm using the correct PHP Version (7.4 for current, 7.2 for legacy).
• I've added comments to any new methods I've created or where else relevant.
• I've replaced magic method usage on DbService classes with the getInstance() static method.
• I've written any documentation for new features or where else relevant in the docs repo.

Description

Check if the task group link will resolve, before creating it on a task page.

Changelog

• added a check to see if the link is accessible, before creating it.

refs:
issues:

Other Information

Docs pull request:

[Dane-2pi]

untested at this point, I need to set up a crm test machine, or someone else can.