re_protos: use async registration by default (protos) (#9537)

### Related

* Part of
[dataplatform#527](https://github.com/issues/assigned?issue=rerun-io%7Cdataplatform%7C527)
* Related [dataplatform
PR](rerun-io/dataplatform#543)

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* Closes #1234
* Part of #1337
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### What
Make async dataset and partition registrations the default registration
method for redap. Keep supporting synchronous registration via the
ManifestRegistry direct endpoint only.

* **This is a breaking change of the redap API**

Signed-off-by: Andrea Reale <andrea@rerun.io>

Author: andrea-reale

crates/store/re_protos/proto/rerun/v1alpha1/manifest_registry.proto

@@ -7,10 +7,11 @@ import "rerun/v1alpha1/common.proto";
 service ManifestRegistryService {
   // --- Write data ---
 
-  // Register new partitions with the Dataset
+  // Register new partitions with the Dataset (asynchronously)
   rpc RegisterWithDataset(RegisterWithDatasetRequest) returns (RegisterWithDatasetResponse) {}
 
-  rpc RegisterWithDatasetAsync(RegisterWithDatasetAsyncRequest) returns (RegisterWithDatasetAsyncResponse) {}
+  // Register new partitions with the Dataset (blocking)
+  rpc RegisterWithDatasetBlocking(RegisterWithDatasetBlockingRequest) returns (RegisterWithDatasetBlockingResponse) {}
 
   // Unimplemented.
   rpc WriteChunks(stream WriteChunksRequest) returns (stream WriteChunksResponse) {}
@@ -135,17 +136,20 @@ message RegisterWithDatasetRequest {
 }
 
 message RegisterWithDatasetResponse {
-  rerun.common.v1alpha1.DataframePart data = 1;
+  rerun.common.v1alpha1.TaskId id = 1;
 }
 
-message RegisterWithDatasetAsyncRequest {
-  // today this just wraps the sync request. This at least avoids
-  // repetition and the two messages going out of sync.
-  RegisterWithDatasetRequest request = 1;
+// TODO(andrea): This is a copy of RegisterWithDatasetRequest.
+// Eventually we _may_ get rid of the sync version; until then,
+// we should make sure that the two objects are in sync.
+message RegisterWithDatasetBlockingRequest {
+  rerun.common.v1alpha1.DatasetHandle entry = 1;
+  repeated DataSource data_sources = 2;
+  rerun.common.v1alpha1.IfDuplicateBehavior on_duplicate = 3;
 }
 
-message RegisterWithDatasetAsyncResponse {
-  rerun.common.v1alpha1.TaskId id = 1;
+message RegisterWithDatasetBlockingResponse {
+  rerun.common.v1alpha1.DataframePart data = 1;
 }
 
 message WriteChunksRequest {