Support for JavaScript and TypeScript file types

[kolyamba2105]

Hi! The theme looks really nice, great job!
It would be cool to add support for JavaScript and TypeScript (.ts and .tsx) file types.
Do you accept PRs? I didn't have a chance to create my own color schemes for vim (neovim) yet, but I can try :)

[katawful]

Feel free to open a PR! For formatting I request that you follow something like the following:

" last filetype already there: {{{
...
" }}}
" JavaScript: {{{
...
" }}}
" TypeScript: {{{
...
" }}}

This is to keep the file neat. Feel free to add your git username after the colon if you wish