Feature/ucsc 135/sidebar menu

[MlKilderkin]

What does this do/fix?

Add maxNestingLevel for navigation block, prevent inserting additional levels on nav menu block maxNestingLevel will work only partially for submenu block. Unfortunately, it is a gutenberg limitation

Note: @bjcooper @Vinsanity The branch also has latest changes from main.

QA

Links to relevant issues

• https://moderntribe.atlassian.net/browse/UCSC-135

Tests

Does this have tests?

• [ ] Yes
• [ ] No, this doesn't need tests because...
• [ ] No, I need help figuring out how to write the tests.