dm1103: fix incorrect button text when a proposal has already been submitted

[sutherlanda]

This PR closes issue: [DM-1103]

Proposed changes:

• The http crud api was intending to return a ResponseValidation wrapping a CWUOpportunityProposal, but it was actually just returning the unwrapped proposal object. This was the root cause of the failed isValid check when determining whether an existing proposal was present or not.
• The fix was to ensure the http crud api wrapped the proposal object in a ResponseValidation. Validation was already being performed by the readMany crud action

[sutherlanda]

Looks good, I think we need these changes in SWU as well

Right, thanks. Added the equivalent fix for SWU as well.