Set MSSQL driver identity and Python User-Agent version

[saurabh500]

Summary

SQL Server currently sees the generic MS-TDS driver and TDSX Rust Client application names. Identify ConnectorX connections explicitly, following the mssql-py-core approach in microsoft/mssql-rs.

• Set the LOGIN7 library name to mssql-tds and the User-Agent library name to connectorx (lowercase).
• Default the application name to ConnectorX, preserving explicit appname URL overrides.
• Initialize the User-Agent driver version from installed Python package metadata, matching connectorx.__version__ including prerelease suffixes. Leave the numeric LOGIN7 version unchanged.
• Include the Python interpreter version in the User-Agent runtime field as Python major.minor.micro, using the numeric fields from sys.version_info without parsing the verbose version string.
• Initialize package version and runtime together once; reject empty or conflicting values. Rust-only builds retain upstream version/runtime defaults unless explicitly configured.

Validation

• Six TDS configuration tests passed, covering library/application names, package version and runtime, repeat initialization, invalid/conflicting values, and unchanged LOGIN7 version.
• Rebuilt and imported the Python extension successfully after the concise runtime change: package version 0.4.7a1, runtime Python 3.12.3.
• The session identity regression passed against SQL Server 2022 in local Docker, covering default and overridden application names.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 45.09%. Comparing base (76a021f) to head (ebdb288).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #992      +/-   ##
==========================================
+ Coverage   44.36%   45.09%   +0.72%     
==========================================
  Files          65       65              
  Lines        9595     9552      -43     
==========================================
+ Hits         4257     4307      +50     
+ Misses       5338     5245      -93     

Files with missing lines	Coverage Δ
connectorx/src/sources/mssql/mod.rs	100.00% <ø> (ø)
connectorx/src/sources/mssql/tds_impl.rs	85.64% <100.00%> (+1.17%)	⬆️

... and 7 files with indirect coverage changes

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