Declaration add form for staff is messy

Problem/Motivation

The form for staff to add a new declaration of a certain type is messy. The fields are oddly ordered and without priority, making it easy for staff to get confused.

Steps to reproduce

(1) Create a new declaration type.
(2) As someone with the permission to make a declararion for others, go to the user context form, enter the donor address, press next, and select the new declararion type
(3) See the resulting form

See screenshot attached.

Proposed resolution

I think the solution needs to involve a number of pieces:

1. Better default weights for fields in a registration type's form display. The OOTB box ordering should be sane for a new registration type. I suggest these default weights:
- the 'Information' pane
- declared date
- any configured fields added to the registration type
- validity
- start date
- end date
- written confirmation sent date
- changed date
- evidence
- revision information
(some of these also effect other record types, probably for the good)

2. The following should be hidden by default in all form modes:
- written confirmation sent date
- changed date
- validity (once #3557144: Allow declaration types to specify field defaults is implemented)

3. Simplify the revision information:
- remove the 'Revision information' label, 'Notes' is plenty
- Alter 'Briefly describe the changes you have made" to something like "You may enter additional notes about the declaration" when the declaration is new.

Remaining tasks

User interface changes

API changes

Data model changes