go: highlight identifiers in parameter lists

Forgot this in #7276. This fixes highlighting of parameters, bringing it
also closer to how we highlight `self` in Rust.

crates/zed/src/languages/go/highlights.scm

@@ -1,6 +1,10 @@
-(identifier) @variable
 (type_identifier) @type
-(field_identifier) @property
+(field_identifier) @variable.member
+
+(keyed_element
+  .
+  (literal_element
+    (identifier) @variable.member))
 
 (call_expression
   function: (identifier) @function)
@@ -15,6 +19,18 @@
 (method_declaration
   name: (field_identifier) @function.method)
 
+(parameter_declaration
+  (identifier) @variable.parameter)
+
+[
+  "("
+  ")"
+  "{"
+  "}"
+  "["
+  "]"
+] @punctuation.bracket
+
 [
   "--"
   "-"