Create propper scope specs for SemesterProcessElegible scopes on volunteer

Trello Card: https://trello.com/c/0a5ZTrOC/186-create-propper-scope-specs-for-semesterprocesselegible-scopes-on-volunteer

MR - volunteer semester process elegible scopes

The merge request contains some pretty complicated scopes that will definitely need to be well tested.

MR dependencies

• Semester Service class !822 (merged)
• volunteer semester process elegible scopes !821 (merged)
• semester process volunteers initial builders before creation !823 (merged)