chore: append template metadata to protobuf config (#20558)

Adds some extra meta data sent to provisioners. Also adds a field
`reuse_terraform_workspace` to tell the provisioner whether or not to
use the caching experiment.

coderd/database/dbfake/dbfake.go

@@ -622,6 +622,7 @@ func (t TemplateVersionBuilder) Do() TemplateVersionResponse {
 	}
 
 	payload, err := json.Marshal(provisionerdserver.TemplateVersionImportJob{
+		TemplateID:        t.seed.TemplateID,
 		TemplateVersionID: t.seed.ID,
 	})
 	require.NoError(t.t, err)