Regular complex fields

By theme design the root form content has pretty styling so that it looks appropriately in the detail sub-apps and dialogs (paddings, flex-box settings, height etc). However, when those recursively apply to the complex field layouts (they're re-used from the form implementation), the UI start to get messy.* We need to prevent most of the rules from leaking into the complex fields, the attached PR attempts to do that for at least the most pressing ones.

Trait fields

Action: Open the url http://localhost:8080/magnoliaAuthor/.magnolia/admincentral#app:pages:browser;/travel/contact/variants/variant-0:treeview and trigger Chose Audience action.

Observation: Some of the fields in the dialog are missing (see screenshot). Additionally, the trait dialog in the new pages app has broken CSS and is visually different from the one in the old app. 

Expectation: The dialog view in the new pages app should be consistent to the one in the old pages app.

Screenshots have been added on how it's on the old app and in the new app.