UX/UI - Information for submission: Proposals cannot be edited after submitted

[CristinaEche]

Requirement: Ensure that the user understands that a proposal cannot be edited after submission.

Implementation:
When the user submits a proposal to an active funding round, inform the user that it cannot be edited. Add a popup reminder before submission.

User Story:

• As a proposal author, I want clear information about what happens to a proposal when it is submitted so that I can reconsider whether I should submit it or not.