Support loading config from flowfuse.yml in preference to flowforge.yml

[hardillb]

Description

Remove one of the last flowforge based configuration option

We should still support flowforge.yml (and flowforge.local.yml) but should prefer flowfuse.yml if present.

Which customers would this be available to

Everyone - CE/Starter/Team/Enterprise

Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate

[hardillb]

This will also need updates to the installer to copy the right default example file to the right place and to check the docker/kube setup