Add topic reader names to logs

[NastyaKa]

Pull request type

• 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?

Topic readers cannot be assigned a diagnostic name, making concurrent readers difficult to distinguish in logs and server-side diagnostics.

Issue Number: N/A

What is the new behavior?

Adds an optional reader_name parameter to topic readers. If omitted, the SDK generates a process-local reader-{i} name that remains stable across reconnects. Reader names are included in initialization requests and SDK logs.

Other information

Includes unit tests, documentation, and updated sync and async examples.

[codecov]

Codecov Report

❌ Patch coverage is 83.01887% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.69%. Comparing base (33b601a) to head (caae48f).

Files with missing lines	Patch %	Lines
ydb/_topic_reader/topic_reader_asyncio.py	82.50%	6 Missing and 1 partial ⚠️
ydb/_topic_reader/topic_reader_sync.py	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #904      +/-   ##
==========================================
+ Coverage   82.66%   82.69%   +0.03%     
==========================================
  Files          99       99              
  Lines       12951    12974      +23     
  Branches     1268     1271       +3     
==========================================
+ Hits        10706    10729      +23     
  Misses       1794     1794              
  Partials      451      451              

Flag	Coverage Δ
integration	80.46% <69.81%> (+0.01%)	⬆️
unit	49.29% <62.26%> (+0.22%)	⬆️

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

Files with missing lines	Coverage Δ
ydb/_grpc/grpcwrapper/ydb_topic.py	86.37% <100.00%> (+0.04%)	⬆️
ydb/_topic_reader/topic_reader.py	91.46% <100.00%> (+0.43%)	⬆️
ydb/topic.py	86.01% <ø> (ø)
ydb/_topic_reader/topic_reader_sync.py	73.17% <60.00%> (+1.01%)	⬆️
ydb/_topic_reader/topic_reader_asyncio.py	87.16% <82.50%> (+0.27%)	⬆️

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.