[New] add jsx-no-padded-children

[golopot]

Fixes #2045

The name of the rule mimics that of eslint rule padded-blocks. Don't know weather it is good or not.

I am concerned of the code duplication in functions checkPaddingTop and checkPaddingBottom, but cannot find a good way to solve it.

[golopot]

I am very unclear about how this rule should be designed.

1. Maybe it should be named jsx-padded-children?
2. Maybe it should be named jsx-children-newline, and do what other *-newline rules do (function-parens-newline, array-bracket-newline, object-curly-newline). However since the concern of Rule proposal: jsx-padded-children #2045 is about disallow empty line, this rule add an option to disallow empty lines, that is, only zero or one newline is allowed.

[ljharb]

jsx-children-newline seems like a better name and model.

[golopot]

Closed this because I couldn't find a satisfactory solution.