Add option to disable cron activity

I've tested this just now and it works as expected. Not setting it to RTBC as for outstanding test coverage.

I agree that we should increase test coverage. But in this case I think we don't need an extra test: "if disabled it's truly not running at cron".

In any case it would be helpful if there is a merge request for this change.

Added changes from #4 to a MR

It works. Just wondering, should a message be logged when cron link checking is skipped?

> should a message be logged when cron link checking is skipped?

I don't think so. Especially on functionality like linkchecker I like to control this directly with own cron jobs without extra modules. So this logging if someone like to add should also get an own config to disable.

I can confirm that the patch is working.
On the other hand, I can also recommend to install Ultimate Cron → module, which provides an easy UI to schedule each module's cron run differently, e.g. linkchecker only once or several times in the night. No patch needed in that scenario.

Thanks for your contribution.
Can we update the it to the latest branch?

solideogloria → changed the visibility of the branch 2.0.x to hidden.

Also, the settings form in 2.x is broken.

🐛 Linkchecker settings form is broken Active

VladimirAus → changed the visibility of the branch 3313343-disable-cron to hidden.

hook_update

for new config property?