Implement RPC skeleton for regular/EC volumes scrubbing. (#8187)

* Implement RPC skeleton for regular/EC volumes scrubbing.

See https://github.com/seaweedfs/seaweedfs/issues/8018 for details.

* Minor proto improvements for `ScrubVolume()`, `ScrubEcVolume()`:

  - Add fields for scrubbing details in `ScrubVolumeResponse` and `ScrubEcVolumeResponse`,
    instead of reporting these through RPC errors.
  - Return a list of broken shards when scrubbing EC volumes, via `EcShardInfo'.

weed/pb/volume_server.proto

@@ -120,6 +120,12 @@ service VolumeServer {
     rpc FetchAndWriteNeedle (FetchAndWriteNeedleRequest) returns (FetchAndWriteNeedleResponse) {
     }
 
+    // scrubbing
+    rpc ScrubVolume (ScrubVolumeRequest) returns (ScrubVolumeResponse) {
+    }
+    rpc ScrubEcVolume (ScrubEcVolumeRequest) returns (ScrubEcVolumeResponse) {
+    }
+
     // <experimental> query
     rpc Query (QueryRequest) returns (stream QueriedStripe) {
     }
@@ -496,6 +502,7 @@ message EcShardInfo {
     uint32 shard_id = 1;
     int64 size = 2;
     string collection = 3;
+    uint32 volume_id = 4;
 }
 
 message ReadVolumeFileStatusRequest {
@@ -632,6 +639,37 @@ message FetchAndWriteNeedleResponse {
     string e_tag = 1;
 }
 
+enum VolumeScrubMode {
+    UNKNOWN = 0;
+    INDEX = 1;
+    FULL = 2;
+}
+
+message ScrubVolumeRequest {
+    VolumeScrubMode mode = 1;
+    // optional list of volume IDs to scrub. if empty, all volumes for the server are scrubbed.
+    repeated uint32 volume_ids = 2;
+}
+message ScrubVolumeResponse {
+    uint64 total_volumes = 1;
+    uint64 total_files = 2;
+    repeated uint32 broken_volume_ids = 3;
+    repeated string details = 4;
+}
+
+message ScrubEcVolumeRequest {
+    VolumeScrubMode mode = 1;
+    // optional list of volume IDs to scrub. if empty, all EC volumes for the server are scrubbed.
+    repeated uint32 volume_ids = 2;
+}
+message ScrubEcVolumeResponse {
+    uint64 total_volumes = 1;
+    uint64 total_files = 2;
+    repeated uint32 broken_volume_ids = 3;
+    repeated EcShardInfo broken_shard_infos = 4;
+    repeated string details = 5;
+}
+
 // select on volume servers
 message QueryRequest {
     repeated string selections = 1;