Use better jsx indentation

[HerringtonDarkholme]

Hey

Maybe you could embed (or use) of https://github.com/MaxMEllon/vim-jsx-pretty for jsx indentation instead of re-implementing it here? Currently I use leafgarland/typescript-vim + vim-jsx-pretty combo for vim-polyglot because it has superior JSX indentation and highlighting experience. On the other hand yats.vim seems to have better syntax support for typescript itself...

Having vim-jsx-pretty functionality here is last stepping stone for best typescript vim plugin. I hope you understand, thank you!

Referring: sheerun/vim-polyglot#428