Share custom objects to record owner where necessary

[LawrenceLoz]

FormulaShare rules which share to users may have records shared to the owner. With previous functionality, share records would not be created for the record owner, meaning if ownership changes at a later point the user and triggers are not set up on the object, the owner could lose access to the record until a FormulaShare batch including this record runs.

Going forwards, rules sharing custom objects to users will create share records for the record owner to ensure that the owner retains access in the event of ownership changes for sharing models where real time triggers/flows are not used.

Note that standard objects do not support sharing to record owners, so functionality for standard objects is unchanged.