chore(mcp): add deployment name field (#415)

- [x] I ran `make setup && make` to update the generated code after editing a `.atd` file (TODO: have a CI check)
- [x] I made sure we're still backward compatible with old versions of the CLI.
      For example, the Semgrep backend need to still be able to *consume* data
	  generated by Semgrep 1.50.0.
      See https://atd.readthedocs.io/en/latest/atdgen-tutorial.html#smooth-protocol-upgrades
	  Note that the types related to the semgrep-core JSON output or the
	  semgrep-core RPC do not need to be backward compatible!
- [ ] Any accompanying changes in `semgrep-proprietary` are approved and ready to merge once this PR is merged

Author: liukatkat

semgrep_metrics.atd

@@ -280,6 +280,7 @@ type finding = {
 
 
 type mcp = {
+    ?deployment_name <ocaml mutable>: string option;
     ?session_id <ocaml mutable>: string option;
     ?num_skipped_rules <ocaml mutable>: int option;
     ?rules <ocaml mutable>: string list option;

semgrep_metrics.py

@@ -908,6 +908,7 @@ def to_json_string(self, **kw: Any) -> str:
 class Mcp:
     """Original type: mcp = { ... }"""
 
+    deployment_name: Optional[str] = None
     session_id: Optional[str] = None
     num_skipped_rules: Optional[int] = None
     rules: Optional[List[str]] = None
@@ -925,6 +926,7 @@ class Mcp:
     def from_json(cls, x: Any) -> 'Mcp':
         if isinstance(x, dict):
             return cls(
+                deployment_name=_atd_read_string(x['deployment_name']) if 'deployment_name' in x else None,
                 session_id=_atd_read_string(x['session_id']) if 'session_id' in x else None,
                 num_skipped_rules=_atd_read_int(x['num_skipped_rules']) if 'num_skipped_rules' in x else None,
                 rules=_atd_read_list(_atd_read_string)(x['rules']) if 'rules' in x else None,
@@ -943,6 +945,8 @@ def from_json(cls, x: Any) -> 'Mcp':
 
     def to_json(self) -> Any:
         res: Dict[str, Any] = {}
+        if self.deployment_name is not None:
+            res['deployment_name'] = _atd_write_string(self.deployment_name)
         if self.session_id is not None:
             res['session_id'] = _atd_write_string(self.session_id)
         if self.num_skipped_rules is not None: