Handle INIT file lock when case is open in ResInsight

[jonjenssen]

When a case is open in ResInsight, the INIT file is locked. This blocks a new OPM flow simulation from being run on existing data.

Workaround is to close the case, then run opm flow, and then reopen the case. However, the user will then have to recreate all plots etc.

Find a way to either keep the INIT file closed unless data is read from it, or to temporarily close the INIT file while the simulator is running.

NOTE: this is when using the resdata file reader.