languages: Add ignore keyword for gomod (#41520)

go 1.25 introduce ignore directive in go.mod to specify directories the
go command should ignore.

ref: https://tip.golang.org/doc/go1.25#go-command


Release Notes:

- Added syntax highlighting support for the new [`ignore`
directive](https://tip.golang.org/doc/go1.25#go-command) in `go.mod`
files

crates/languages/src/gomod/highlights.scm

@@ -7,6 +7,7 @@
   "exclude"
   "retract"
   "module"
+  "ignore"
 ] @keyword
 
 "=>" @operator

crates/languages/src/gomod/structure.scm

@@ -27,3 +27,9 @@
   ("(") @structure.open
   (")") @structure.close
 )
+
+(ignore_directive
+  "ignore" @structure.anchor
+  ("(") @structure.open
+  (")") @structure.close
+)