Support multiple tree-sitter grammars

[Damien Cassou]

Hi,

some files may consist of several parts requiring different tree-sitter
grammars. For example, a JavaScript file may have its documentation
written with jsdoc: JavaScript and jsdoc have a tree-sitter grammar
each.

Is there a way to use a tree-sitter grammar in parts of the file and
another one in other parts? There could be a main grammar and secondary
grammars would be activated on some kinds of nodes of the main one.

Best

-- 
Damien Cassou

"Success is the ability to go from one failure to another without
losing enthusiasm." --Winston Churchill