Add TopicClient.reset_offset to rewind a consumer's committed offsets.

[nshestakov]

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

The topic client can commit an offset for one partition (commit_offset) but cannot rewind a consumer's committed offsets. Python client for TopicService.ResetOffset, already available in the C++ SDK (ydb-platform/ydb#54149).

Issue Number: N/A

What is the new behavior?

TopicClient.reset_offset / TopicClientAsyncIO.reset_offset rewind a consumer's committed offsets on every topic partition, including inactive partitions left after a split or merge.

driver.topic_client.reset_offset(path, consumer, to=ydb.TopicResetOffset.EARLIEST)
driver.topic_client.reset_offset(path, consumer, to=ydb.TopicResetOffset.LATEST)
driver.topic_client.reset_offset(path, consumer, to=written_at)  # datetime

A datetime selects the first message whose write timestamp is greater than or equal to that time. If no such message exists, the partition end offset is used.

Partitions are updated independently: the call is not atomic, and a failure may still leave some partitions already rewritten. Any active read session of this consumer is dropped. The call is retried on cancellation the same way as commit_offset.

Other information

Stubs for protobuf 3–6 were regenerated with ResetOffset. ydb-api-protos does not contain this RPC yet, so the submodule pointer is unchanged; the proto additions used for generation are not part of this commit. The next regeneration from the current pin will drop ResetOffset until that change lands in ydb-api-protos.

[codecov]

Codecov Report

❌ Patch coverage is 97.14286% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 82.70%. Comparing base (87d561e) to head (ed11f9a).

Files with missing lines	Patch %	Lines
ydb/_grpc/grpcwrapper/ydb_topic.py	95.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #907      +/-   ##
==========================================
+ Coverage   82.66%   82.70%   +0.03%     
==========================================
  Files          99       99              
  Lines       12953    12987      +34     
  Branches     1268     1273       +5     
==========================================
+ Hits        10708    10741      +33     
  Misses       1794     1794              
- Partials      451      452       +1     

Flag	Coverage Δ
integration	80.48% <91.42%> (+0.02%)	⬆️
unit	49.14% <80.00%> (+0.07%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
ydb/_apis.py	100.00% <100.00%> (ø)
ydb/_grpc/grpcwrapper/ydb_topic_public_types.py	100.00% <100.00%> (ø)
ydb/topic.py	86.58% <100.00%> (+0.56%)	⬆️
ydb/_grpc/grpcwrapper/ydb_topic.py	86.51% <95.00%> (+0.18%)	⬆️

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