feat: add OpenIn option to coder_app (#15743)

This PR is the coder/coder part of [the open_in parameter
issue](https://github.com/coder/terraform-provider-coder/issues/297)
aiming to add a new optional parameter to choose how to open modules.

This PR is heavily linked [to this
PR](https://github.com/coder/terraform-provider-coder/pull/321).

ℹ️ For now, some integrations tests can not be pushed as it requires a
release on the terraform-provider repo.

codersdk/agentsdk/convert.go

@@ -255,6 +255,7 @@ func AppFromProto(protoApp *proto.WorkspaceApp) (codersdk.WorkspaceApp, error) {
 		},
 		Health: health,
 		Hidden: protoApp.Hidden,
+		OpenIn: protoApp.OpenIn,
 	}, nil
 }
 
@@ -285,6 +286,7 @@ func ProtoFromApp(a codersdk.WorkspaceApp) (*proto.WorkspaceApp, error) {
 		},
 		Health: proto.WorkspaceApp_Health(health),
 		Hidden: a.Hidden,
+		OpenIn: a.OpenIn,
 	}, nil
 }