Add 'enforce' support for integrations config

[amimas]

Several config sections of gitlabform supports the usage of enforce: true. This allows automatically deleting the resources under that section that is not present in gitlabform config. This feature request is to add same support to the integrations config.

[adam-moss]

This may be slightly more tricky than it first appears. E.g. where an integration needs to authenticate on first use. I'm sure we hit this ourselves with testing @TimKnight-DWP ?

[TimKnight-DWP]

Honestly I don't recall, but I can definetly see the problem where an OAuth loop gets triggered within GLF run

[amimas]

I have used only a couple integrations, I think. The enforce feature will only try to delete an integration. Is there any authentication involved at this stage?