Implement validation for seqvars module

[holtgrewe]

Is your feature request related to a problem? Please describe. In #1737, we implement the seqvars module. Validation (such as ensuring states) has not been implemented.

Describe the solution you'd like We need to validate states to track the allowed states.

Describe alternatives you've considered N/A

Additional context

• #1737

[holtgrewe]

Also, we need properly launching of query executions.