Add instantiate typekit

[timotheeguerin]

Use case #7469 and #9729

There is a few ways we could consider this.

// 1. Evaluate expr
$.type.instantiate("Array<Foo>")

// 2. Pass args manually
$.type.instantiate($.type.resolve("Array"), [$.type.resolve("Foo")])

2. Is probably needed for more control but it is also right now blocked as $.type.resolve("TemplateDecl") won't resolve it, need a flag to allow resolving the declaration