Enforce JSX newline+indentation

[mattrabe]

We should enforce how JSX attributes are placed on new lines and indented.

We should enforce that the new lines are in the right place. We're seeing PRs with eg:

<View style={{
  color: 'blue',
  width: 123,
}}
>

Attributes need to be on a new line and indented - style needs to be the start of the new line - like this:

<View
  style={{
    color: 'blue',
    width: 123,
  }}
>

I'm personally torn on whether we should always require new lines, vs start requiring new lines once there are 1,2,3 attributes...