Problem:
Vimscript ftplugins that inherit a base ftplugin often use explicit
`runtime! ftplugin/foo.vim` patterns. This skips corresponding Lua
ftplugins, unlike top-level ftplugin loading.

Solution:
Use the existing `{vim,lua}` patterns for bang runtime imports while
preserving each call's current lookup breadth.

Port javascript and javascript react ftplugins only.

Problem:    Errors when using javascriptreact.
Solution:   Use ":runtime" instead of ":source". (closes vim/vim#4875)
https://github.com/vim/vim/commit/4fb15c647658b15230c61857c644230a03881904

Problem:    Cannot recognize .jsx and .tsx files.
Solution:   Recognize them as javascriptreact and typescriptreact.
            (closes vim/vim#4830)
https://github.com/vim/vim/commit/92852cee3fcff1dc6ce12387b234634e73267b22