Flatten | DbMetaDataFactory -> SqlMetaDataFactory

[edwardneal]

Description

This continues some of the earlier work from #3435, which replaced a layer of inheritance between DbConnectionFactory and SqlConnectionFactory, and #3773, which does the same between SqlInternalConnection and SqlInternalConnectionTds.

Here, we remove DbMetaDataFactory and fold its responsibilities into SqlMetaDataFactory. These are comparatively large files, so it's simplest to move commit-by-commit with whitespace changes hidden. I proceed in stages:

1. Replace necessary references to DbMetaDataFactory with SqlMetaDataFactory.
2. Identify a dead code path: the ability to supply a normalized (i.e. zero-padded) server version string. SqlClient never used this capability.
3. Perform general code cleanup prior to the merge. This cleanup was a handful of fairly small points which are designed to bring the final file into alignment with the current code style.
4. Move methods and constants. At this stage, methods are being copied and pasted from source to destination (plus some touch-ups of their scope between protected and private as appropriate.)
5. Post-hoc touch-ups to remove the inheritance and unused methods.

Issues

No associated issues.

Testing

Automated tests continue to pass.

[benrr101]

Looks good!

[benrr101]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[codecov]

Codecov Report

❌ Patch coverage is 89.85240% with 55 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.20%. Comparing base (995df25) to head (0722b56).
⚠️ Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
...src/Microsoft/Data/SqlClient/SqlMetaDataFactory.cs	89.77%	55 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (995df25) and HEAD (0722b56). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (995df25)	HEAD (0722b56)
addons	1	0

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3818      +/-   ##
==========================================
- Coverage   76.61%   69.20%   -7.41%     
==========================================
  Files         274      267       -7     
  Lines       43393    66325   +22932     
==========================================
+ Hits        33247    45903   +12656     
- Misses      10146    20422   +10276     

Flag	Coverage Δ
addons	?
netcore	69.17% <89.81%> (-7.51%)	⬇️
netfx	68.57% <89.81%> (-7.63%)	⬇️

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