Reduce UNT0043 false positives for platform and version guards

[Sebastien Lebreton (sailro)]

Checklist

• I have read the Contribution Guide.
• There is an approved issue describing the change when contributing a new analyzer or suppressor (not applicable: this fixes an existing analyzer).
• I have added tests that prove my fix is effective or that my feature works.
• I have added necessary documentation.

Short description of what this resolves

UNT0043 can mistake intentionally inactive platform and Unity-version symbols for typos because it only compares them with symbols enabled in the current build. Reported examples include UNITY_6000_4_OR_NEWER and UNITY_6000_5_OR_NEWER being suggested as UNITY_6000_0_OR_NEWER, and UNITY_PS4 being suggested as UNITY_64.

Make detection more conservative without maintaining a catalog of Unity platforms or versions. This remains a heuristic: valid optional symbols can still resemble enabled symbols, and typos for inactive platforms may go undetected.

Changes proposed in this pull request

• Exempt well-formed UNITY_X, UNITY_X_Y, UNITY_X_Y_Z, and UNITY_X_Y_OR_NEWER version symbols independently of the installed Unity version.
• Preserve numeric components, including their boundaries, when suggesting a correction.
• Replace the length-dependent edit-distance threshold with a single insertion, deletion, substitution, or adjacent transposition; require a unique candidate instead of breaking ties alphabetically.
• Use a realistic platform configuration in the compound-condition test, add regressions and code-fix coverage, and document the behavior and limitations.

Validation

• Built the test project successfully and ran all 66 ConditionalCompilationSymbolTypoTests cases successfully.
• Exercised the analyzer on the 11 affected Burst/Input System package files with both Editor and Player defines: all 22 file/configuration combinations produced no UNT0043 diagnostics, while a genuine typo control remained detected.