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/cpp/embedding.scm

@@ -0,0 +1,61 @@
+(
+    (comment)* @context
+    .
+    (function_definition
+        (type_qualifier)? @name
+        type: (_)? @name
+        declarator: [
+            (function_declarator
+                declarator: (_) @name)
+            (pointer_declarator
+                "*" @name
+                declarator: (function_declarator
+                declarator: (_) @name))
+            (pointer_declarator
+                "*" @name
+                declarator: (pointer_declarator
+                    "*" @name
+                declarator: (function_declarator
+                    declarator: (_) @name)))
+            (reference_declarator
+                ["&" "&&"] @name
+                (function_declarator
+                declarator: (_) @name))
+        ]
+        (type_qualifier)? @name) @item
+    )
+
+(
+    (comment)* @context
+    .
+    (template_declaration
+        (class_specifier
+            "class" @name
+            name: (_) @name)
+            ) @item
+)
+
+(
+    (comment)* @context
+    .
+    (class_specifier
+        "class" @name
+        name: (_) @name) @item
+    )
+
+(
+    (comment)* @context
+    .
+    (enum_specifier
+        "enum" @name
+        name: (_) @name) @item
+    )
+
+(
+    (comment)* @context
+    .
+    (declaration
+        type: (struct_specifier
+        "struct" @name)
+        declarator: (_) @name) @item
+)