Use EditEngine for Harbormaster Build Plans, fix some crumbs/mobile stuff

Summary:
Ref T10457.

• Use EditEngine for Build Plans.
• Fix some minor issues with crumbs being inconsistent.
• Fix some minor issues with mobile menus not being consistent/available.

Test Plan:

• Created and edited build plans.
• Poked around in mobile width, verified mobile menu had the right stuff in it.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10457

Differential Revision: https://secure.phabricator.com/D15357