Add a configurable option for the modified script action

[Igladyshev]

Is your feature request related to a problem? Please describe.
Currently in our team we are using an in-house implemented db changes which behaves almost 100% as schemachange, and that was the reason for decision to adopt schemachange.
One of missing features is a configurable action on the "Script Checksum" check outcome. In our system we have three options:

1. ERROR - we use it for deployments to master/cert/prod branches
2. EXECUTE - we use for feature branches
3. IGNORE - this is the schemachange's behaviour and we don't use it at all

Describe the solution you'd like

1. If we had the SCRIPT_CHECKSUM_CHANGED_ACTION=ERROR, we would guard ourself from unwanted changes and still know about them, since the CI/CD pipeline would fail.
2. If we had the SCRIPT_CHECKSUM_CHANGED_ACTION=EXECUTE - the development cycle would be quicker, since a developer won't need help from a DBA to deal with applied changes log

Describe alternatives you've considered
I didn't find any alternatives

Additional context
No additional context