gRPC: Add protocol and comms implementation for FetchRecording (#7909)

### What
This basically makes it possible to use the storage node as a proxy to
fetch the full contents of all the chunks for the giving recording from
the store.

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using examples from latest `main` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/7909?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/7909?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG
* [x] If applicable, add a new check to the [release
checklist](https://github.com/rerun-io/rerun/blob/main/tests/python/release_checklist)!
* [x] If have noted any breaking changes to the log API in
`CHANGELOG.md` and the migration guide

- [PR Build Summary](https://build.rerun.io/pr/7909)
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crates/store/re_remote_store_types/.gitattributes

@@ -0,0 +1 @@
+src/v0/rerun.remote_store.v0.rs linguist-generated=true

crates/store/re_remote_store_types/proto/rerun/v0/remote_store.proto

@@ -7,6 +7,7 @@ import "rerun/v0/common.proto";
 service StorageNode {
     rpc ListRecordings(ListRecordingsRequest) returns (ListRecordingsResponse) {}
     rpc Query(QueryRequest) returns (stream QueryResponse) {}
+    rpc FetchRecording(FetchRecordingRequest) returns (stream FetchRecordingResponse) {}
     rpc GetRecordingMetadata(GetRecordingMetadataRequest) returns (GetRecordingMetadataResponse) {}
     // TODO(zehiko) - should this be singular recording registration? Currently we can have 1 rrd => many recordings
     rpc RegisterRecordings(RegisterRecordingsRequest) returns (RegisterRecordingsResponse) {}
@@ -115,3 +116,20 @@ message RecordingInfo {
 enum RecordingType {
     RRD = 0;
 }
+
+// ----------------- FetchRecording -----------------
+
+message FetchRecordingRequest {
+    RecordingId recording_id = 1;
+}
+
+// TODO(jleibs): Eventually this becomes either query-mediated in some way, but for now
+// it's useful to be able to just get back the whole RRD somehow.
+message FetchRecordingResponse {
+    // TODO(zehiko) we need to expand this to become something like 'encoder options'
+    // as we will need to specify additional options like compression, including schema
+    // in payload, etc.
+    EncoderVersion encoder_version = 1;
+    // payload is raw bytes that the relevant codec can interpret
+    bytes payload = 2;
+}