fix: set form logo default value when creating form document

[karrui]

!! Will probably need a DB migration script to populate old forms (that did not update their start pages) with a default form logo state

Problem

Creating a new form does not create a default startPage.logo nested document, resulting in a new form not having a default form logo state.

This PR populates startPage.logo with its default state.

Solution

Breaking Changes

• Yes - this PR contains breaking changes
  • Details ...
• No - this PR is backwards compatible
  • If rolled back... just means new documents don't have a default state

Improvements:

• fix: set default form logo schema on form document creation

Tests

• tests have been updated

Manual tests

• Create a new email form. Check that the returned form object from the server now has startPage.logo.state = "DEFAULT"