[refactor] #3901: Add method to define parameter in executor migrate entrypoint

[dima74]

Description

• Added method add_parameter which can be called from executor (in migrate entrypoint) to define new executor parameter
• Added test which demonstrates how executor can use it, as suggested here
• Note that this PR was mostly implemented before discussion in dynamic parameter value #4352, so potentially this should be implemented differently. E.g. if it will be decided to store executor parameters in Domain::metadata, then there will be no need for add_parameter method since executor parameter will be defined using SetKeyValue ISI
• Note that I didn't removed NewParameter ISI since it is currently used to define chain-wide parameters (for wasm engine and sumeragi), and potentially chain-wide parameters should be defined/stored differently as discussed in dynamic parameter value #4352 (comment)

Linked issue

Closes #3901
Related: #4352
Related: #4310

Benefits

Checklist

• I've read CONTRIBUTING.md
• I've used the standard signed-off commit format (or will squash just before merging)
• All applicable CI checks pass (or I promised to make them pass later)
• (optional) I've written unit tests for the code changes
• I replied to all comments after code review, marking all implemented changes with thumbs up