Expose financial type on Price Set form for all Used For options and use this as default for price fields and price field values

Allowing users to set a default Financial Type at the price set level will provide convenience for the bulk of users who do not need to configure different financial types for price fields / options within a price set.

1. Remove logic which hides Financial Type dropdown on Price Set form (CRM_Price_Form_Set) based on 'extends' value. Always show the dropdown. Modify form rule to just make the field REQUIRED in all cases (rather than just for membership price sets).

2. Change field label from 'Financial Type (Membership Fees)' to 'Default Financial Type'

3. Use price_set.financial_type_id as the default when exposing that dropdown in CRM_Price_Form_Field. EXCEPT for membership price sets - we still get default from membership_type.financial_type_id if user selects a membership type for a price_field_value row.