BlElement: Review layout-related protocols and API

[tinchodias]

First point is about "view - configuration" protocol. We don't use the term "view", and the methods in this protocol fit well in "api - layout", where padding: and margin: are (they expose layout constraints' API) :

[tinchodias]

There are other methods that expose layout constraints' API that could be in "api - layout" protocol: position, size, width, height. These methods are categorized in "api - bounds" protocol.

[tinchodias]

Now my analysis on "layout utilities" protocol, that has 2 methods:

• forceLocalLayout with no senders (to be removed?)
• forceLayout, whose comment starts with "Do no use me" but has more than 300 senders on my image (mostly from tests)

Maybe this protocol can be merged into "private - layout", as it's not designed as part of the API for users.