languages: add highlighting for go.mod (#7137)

Release Notes:

- Added syntax highlighting for go.mod files. Fixes #7133 

<img width="863" alt="image"
src="https://github.com/zed-industries/zed/assets/8725798/dc521a02-c53a-44aa-b0c1-eebf31835679">

crates/zed/Cargo.toml

@@ -115,6 +115,7 @@ tree-sitter-embedded-template.workspace = true
 tree-sitter-gleam.workspace = true
 tree-sitter-glsl.workspace = true
 tree-sitter-go.workspace = true
+tree-sitter-gomod.workspace = true
 tree-sitter-haskell.workspace = true
 tree-sitter-heex.workspace = true
 tree-sitter-html.workspace = true

crates/zed/src/languages.rs

@@ -122,6 +122,7 @@ pub fn init(
         tree_sitter_go::language(),
         vec![Arc::new(go::GoLspAdapter)],
     );
+    language("gomod", tree_sitter_gomod::language(), vec![]);
     language(
         "zig",
         tree_sitter_zig::language(),

crates/zed/src/languages/gomod/config.toml

@@ -0,0 +1,7 @@
+name = "Go Mod"
+path_suffixes = ["mod"]
+line_comments = ["//"]
+autoclose_before = ")"
+brackets = [
+    { start = "(", end = ")", close = true, newline = true}
+]

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

@@ -0,0 +1,18 @@
+[
+  "require"
+  "replace"
+  "go"
+  "toolchain"
+  "exclude"
+  "retract"
+  "module"
+] @keyword
+
+"=>" @operator
+
+(comment) @comment
+
+[
+(version)
+(go_version)
+] @string

crates/zed/src/languages/gomod/structure.scm

@@ -0,0 +1,29 @@
+(require_directive
+  "require" @structure.anchor
+  ("(") @structure.open
+  (")") @structure.close
+)
+
+(exclude_directive
+  "exclude" @structure.anchor
+  ("(") @structure.open
+  (")") @structure.close
+)
+
+(module_directive
+  "module" @structure.anchor
+  ("(") @structure.open
+  (")") @structure.close
+)
+
+(replace_directive
+  "replace" @structure.anchor
+  ("(") @structure.open
+  (")") @structure.close
+)
+
+(retract_directive
+  "retract" @structure.anchor
+  ("(") @structure.open
+  (")") @structure.close
+)