Fix admin user experience failures. Cleanup janky form implementations and unify all the different styles of form fields and action lists we are using across all the pages.

We should be able to express all build options in the YAML file. Once this is done, we can then deprecate the database for build settings for projects with a YAML file. Steps:

• Add all build options to YAML file
• Add state to Project that a YAML file is in use
• Disable build options in web UI for Projects with YAML file

New builder features, to help introduce better user experience into our building. This is secondary to builder stability, though there is some overlap in goals here.

Some features that we would love to have in Read the Docs, but we can't focus on just yet. If you are a new contributor and want a new feature to implement, look no further.