fix(plugin-form-builder): use escapeHTML on submission data in serializeLexical

[NorthBlue333]

Description

Fixes #8109 Note this should also be merge in payload/beta!

• [X] I have read and understand the CONTRIBUTING.md document in this repository.

Type of change

• [X] Bug fix (non-breaking change which fixes an issue)

Checklist:

• [ ] I have added tests that prove my fix is effective or that my feature works
• [X] Existing test suite passes locally with my changes