[Rust] Add builder API for creating workflows

`Workflow::new` is replaced by `Workflow::build` that returns a
`Builder` type that supports the operations that mutate a workflow, such
as registering activities.

`Workflow::instance` is replaced by `Workflow::get` to make clear that
it is intended to look up an existing workflow.

`Workflow::cloned` is introduced to wrap the common pattern of
retrieving an existing workflow and cloning it with the same name in
order to modify it.

`Builder::activity_before` / `Builder::activity_after` are introduced to
wrap the common pattern of registering an activity then inserting it
before or after a given activity.

1 files changed, 4 insertions, 1 deletions

diff --git a/plugins/warp/src/plugin.rs b/plugins/warp/src/plugin.rs
index 3306801d..ee778062 100644
--- a/plugins/warp/src/plugin.rs
+++ b/plugins/warp/src/plugin.rs
@@ -102,7 +102,10 @@ pub extern "C" fn CorePluginInit() -> bool {
     // Register our highlight render layer.
     HighlightRenderLayer::register();
 
-    workflow::insert_workflow();
+    if workflow::insert_workflow().is_err() {
+        log::error!("Failed to register WARP workflow");
+        return false;
+    }
 
     // TODO: Make the retrieval of containers wait on this to be done.
     // TODO: We could also have a mechanism for lazily loading the files using the chunk header target.