Based on https://github.com/prettier/prettier/pull/2676
* Thread `path` and `options` through helpers so we don't need to add `needsParens` onto the AST node anymore (mutation)
* Pull test call detection logic out into helper method so it can be re-used for arrow function parens
* Add arrow function parens option implementation (avoid/always)
* Don't break arrow function parens around (done) in test call
* Now JSX-mode ternaries only break if they need to.
* Only the outermost ternary in a chain of JSX-mode ternaries will become a group.
* We don't wrap null in parens when breaking JSX-mode ternaries.
This commit also improves the test coverage and explanation in tests/jsx/conditional-expression.js.
* Arrow Function Expressions returning JSX will now add parens when the JSX breaks
* Conditional expressions within (or containing) JSX are formatted in a more natural way (for JSX), especiall when chained
* JSX in logical expressions (|| or &&) is always wrapped in parens
Fixes#2208
suchipi