derivation_worker: log client request info to scuba

Summary: Add logging of client request info objects to scuba in the derviation worker.  This requires us to stop using a single context object, and instead construct a new one for each request.  For now we just create a new client info.  We will accept one from the derived data service in a later diff.

Reviewed By: RajivTS

Differential Revision: D49743404

fbshipit-source-id: 68b16b265593a8a4f487976f96e4d3e62904b543

eden/scm/lib/clientinfo/src/request_info.rs

@@ -117,6 +117,7 @@ pub enum ClientEntryPoint {
     LandService,
     LFS,
     DerivedDataService,
+    DerivationWorker,
     ISL,
     SCS_CLI,
 }
@@ -178,6 +179,7 @@ impl Display for ClientEntryPoint {
             ClientEntryPoint::LandService => "landservice",
             ClientEntryPoint::LFS => "lfs",
             ClientEntryPoint::DerivedDataService => "derived_data_service",
+            ClientEntryPoint::DerivationWorker => "derivation_worker",
             ClientEntryPoint::ISL => "isl",
             ClientEntryPoint::SCS_CLI => "scsc",
         };