[Feature] Moving selected_tests inside the TestRunExecution

[antonio-amjr]

Moving selected_tests API parameter to inside the Test Run Execution model, schema and CRUD files.
That way we simplify removing one parameter from the creation API.

The following changes were provided:

• A new DB revision file was manually created so the new column selected_test, added into the TestRunExecution model, is filled with the information needed (gathered from tables inside the DB). This new column is mandatory as we'll always use this dictionary to create new Test Runs.
• The create_test_run_execution() API method had its selected_test parameter moved inside the test_run_execution_in object, as a dictionary blob.
• The CRUD file was updated to use only one create method once again.
• A dictionary was added to the schema for the selected_tests data.
• The model file maps the dictionary blob to a JSON type in DB.
• Related changes on unit tests and utils files.