Add kotlin language (#1689)

* Add kotlin language

Queries taken from https://github.com/nvim-treesitter/nvim-treesitter/blob/master/queries/kotlin seem to work well enough for my needs though I don't use kotlin heavily.

* Update lang-support doc

* Updates the kotlin highlight query to use helixs scopes

* Updates the queries from PR feedback

* Adds 'shallow = true' to gitmodules

* Removes kotlin locals.scm

* Remove blank line

Co-authored-by: Ivan Tham <pickfire@riseup.net>

Co-authored-by: Ivan Tham <pickfire@riseup.net>

runtime/queries/kotlin/folds.scm

@@ -0,0 +1,17 @@
+[
+	(import_list)
+
+	(when_expression)
+	(control_structure_body)
+
+	(lambda_literal)
+	(function_body)
+	(primary_constructor)
+	(secondary_constructor)
+	(anonymous_initializer)
+
+	(class_body)
+	(enum_class_body)
+
+	(interpolated_expression)
+] @fold