Mode names for C-like tree-sitter modes

[Yuan Fu]

Thanks to Theo’s great work, we now have tree-sitter powered major modes for C, 
C++, Java, JSON, CSS. Right now they are named c-ts-mode, c++-ts-mode, 
java-ts-mode, etc. And c-ts-mode and c++-ts-mode inherits from a dummy mode 
c-ts-mode--base-mode.

I think it’s fair to make C, C++ and Java modes independent, since all the 
cc-mode options are invalidated when we use tree-sitter. However, their name 
could be improved, IMO. But I can’t think of anything better than c-ts-mode :-)

(neo-c-mode… just saying)

c-ts-mode--base-mode should probably be a public mode, since the intention 
(IIUC) is enable users to configure C and C++ together, by adding hooks to this 
base-mode. So something like c-base-mode or c-ts-base-mode?

CSS and JSON could be merged with current modes, I think. Css-ts-mode could 
merge with css-mode, and json-ts-mode could be merged with js-json-mode. Or we 
can just have a dedicated json-mode.

Theo, WDYT?

Yuan