feat(#1340): simplify defect assertions in test YAML files

[volodya-lombrozo]

This PR simplifies test YAML files by allowing defects to be specified declaratively in a structured format instead of requiring manual XPath assertions. The XtDefects class now automatically generates the appropriate XPath expressions from defects entries containing severity and line attributes, eliminating repetitive boilerplate across 315+ test files.

Fixes #1340

[volodya-lombrozo]

@rultor merge

[rultor]

@rultor merge

@volodya-lombrozo OK, I'll try to merge now. You can check the progress of the merge here.

[rultor]

@rultor merge

@volodya-lombrozo Done! FYI, the full log is here (took me 12min).

[0crat]

@volodya-lombrozo Thanks for the contribution! You've earned +4 points for this: +16 as a basis; -4 for too many hits-of-code (1466 >= 100); -8 for way too many hits-of-code (1466 >= 400). Please, keep them coming. Your running score is +360; don't forget to check your Zerocracy account too).