MBS-5863: Display work attributes in the work sidebar
MBS-5863: Correctly translate work attribute type names
MBS-5863: Restore Work->load_writers call in work/index action
MBS-5863: Add Work->allowed_attribute_values to determine allowed values
MBS-5863: Allow Work form submissions to edit work attributes
MBS-5863: Edit work attributes with the value of form submission
MBS-5863: Implemented the essentials for work attributes HTML forms
MBS-5863: Improve formatting and allow removing attributes
MBS-5863: Allow editing existing work attributes
Correctly parse value not type_id
MBS-5863: Display edits to work attributes
MBS-5863: Allow creating works with attributes
MBS-5863: Display work attributes for newly created works
MBS-5863: Do not apply multiple bindings for work attribute editing
MBS-5863: Editing work attributes should not be an autoedit
MBS-5863: Display work attributes even if there are no other work properties
MBS-5863: Clear attribute value when attribute type changes
MBS-5863: Add statistics to view work attribute distribution
MBS-5863: Correctly inflate attributes for old work edits
MBS-6989: Work attribute <selects> should be prefixed with empty values

These empty values don't form a valid submission, but they help the user
avoid submitting the wrong data.