[Enhancement] Do not automatically create matching single quote for generic type declaration

[mrvicadai]

What & Why?

Take writing the following block of ReasonML for example:

let fold: (('b, 'a) => 'b, 'b) => 'b;

When we intend to type 'a, the editor automatically creates a pair of single quotes '' therefore we have to manually remove the closing '. It's a minor annoyance but could really save a lot of typing if ' does not automatically expand into a pair of single quotes.