Update connection's configuration before saving it

[sebjulliand]

Changes

This PR makes sure the connection's configuration gets updated before it gets saved, so the functions triggered by onCodeForIBMiConfigurationChange who access the current configuration (i.e. using instance.getConfig()) gets the updated configuration (and not the one before it gets updated).

How to test this PR

1. Open the connection settings
2. Got to the Source Code tab
3. Change the Read only mode checkbox

• [ ] Without the PR: the connection's icon in the status bar doesn't get update to reflect the read only mode state. It updates if another the settings are re-opened and saved again.
• [x] With the PR: the icon gets updated immediately after the settings are saved.

Checklist

• [x] have tested my change