Add a timeout option to connectivity checks
Summary
Allow configuring the timeout for connectivity checks (used to be hardcoded to 20s)
Purpose
We use this to make failover from our primary (hardwired ethernet) interface to a cell modem backup faster
Checklist
Please read https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/blob/main/CONTRIBUTING.md before opening the merge request. In particular, check that:
-
the subject for all commits is concise and explicative -
the message for all commits explains the reason for the change -
the source is properly formatted -
any relevant documentation is up to date -
you have added unit tests if applicable -- (didn't see any connectivity tests, let me know if I just missed it!) -
the NEWS file is updated when the change deserves to be mentioned, for example for new features, behavior changes, API deprecations, etc.