chore: Extract languages from zed crate (#8270)

- Moves languages module from `zed` into a separate crate. That way we
have less of a long pole at the end of compilation.
- Removes moot dependencies on editor/picker. This is totally harmless
and might help in the future if we decide to decouple picker from
editor.

Before:
```
Number of crates that depend on 'picker' but not on 'editor': 1
Total number of crates that depend on 'picker': 13
Total number of crates that depend on 'editor': 30
```
After:
```
Number of crates that depend on 'picker' but not on 'editor': 5
Total number of crates that depend on 'picker': 12
Total number of crates that depend on 'editor': 26
```
The more crates depend on just picker but not editor, the better in that
case.

Release Notes:

- N/A

crates/languages/src/gomod/config.toml

@@ -0,0 +1,8 @@
+name = "Go Mod"
+grammar = "gomod"
+path_suffixes = ["mod"]
+line_comments = ["//"]
+autoclose_before = ")"
+brackets = [
+    { start = "(", end = ")", close = true, newline = true}
+]

crates/languages/src/gomod/highlights.scm

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

crates/languages/src/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
+)