feat(contributors): Support populating scan metadata to results for contributor processing (#401)

# Description

To support processing contributors, we want to associate each
contribution with the driving scan for billing.

- [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!
- [N/A] Any accompanying changes in `semgrep-proprietary` are approved
and ready to merge once this PR is merged

Author: zzeleznick

semgrep_output_v1.atd

@@ -1620,6 +1620,7 @@ type project_metadata = {
 
 }
 
+(* Scan metadata generated by the CLI during the scan process. *)
 type scan_metadata = {
   cli_version: version;
   unique_id: uuid; (* client generated uuid for the scan *)
@@ -1745,6 +1746,23 @@ type ci_scan_results = {
    (* this data was originally sent to /complete, but we want to start sending
     * it to /results *)
    ?dependencies: ci_scan_dependencies option;
+
+   (* filled in by the backend to associate scan results with the driving scan*)
+   ?metadata: ci_scan_metadata option;
+}
+
+(* Scan metadata populated by the backend after receiving
+ * the scan results from the CLI via POST request to
+ * /scans/<int:scan_id>/results
+ *)
+type ci_scan_metadata = {
+  scan_id: int;
+  deployment_id: int;
+  repository_id: int; (* stored as int in our app db *)
+  repository_ref_id: int; (* stored id for a branch or tag *)
+  enabled_products: product list;
+  git_commit: sha1 nullable;
+  git_ref: string nullable;
 }
 
 (* See https://semgrep.dev/docs/usage-limits