feat(highlights)!: enforce documented captures (#6232)

Problem: Allowing undocumented "secret" (sub)captures makes it harder
to write comprehensive colorschemes and catch inconsistent captures.

Solution: Only allow captures listed in CONTRIBUTING.md. Add useful
(cross-language) subcaptures and drop language-specific or too niche
ones.

Follow-up: Adding further `*.builtin` captures and changing queries to
use them.

Language-specific subcaptures should instead be added in user config or
a custom language plugin.

queries/strace/highlights.scm

@@ -16,9 +16,10 @@
 (syscall) @function.builtin
 
 ; Literals
-(integer) @number
-
-(pointer) @number.special
+[
+  (integer)
+  (pointer)
+] @number
 
 (value) @label