3267 xmir2xmir tests

[levBagryansky]

Closes #3267

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PR-Codex overview

This PR focuses on adding XcopCondition to skip tests without xcop. It also includes YAML files for xmir2xmir tests.

Detailed summary

• Added XcopCondition to skip tests without xcop
• Added YAML files for xmir2xmir tests
• Updated XSL files with examples in YAML
• Added MIT License to YAML files

The following files were skipped due to too many changes: eo-maven-plugin/src/test/resources/org/eolang/maven/xmir2xmir/aligns-test-classes.yaml, eo-maven-plugin/src/test/java/org/eolang/maven/Xmir2Xmir.java

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[levBagryansky]

@maxonfjvipon please review

[levBagryansky]

@yegor256 please check

[maxonfjvipon]

@yegor256 please check

[yegor256]

@levBagryansky @maxonfjvipon didn't we agree that comparing XML to XML is a bad idea and we should use XPath instead?

[maxonfjvipon]

@yegor256 we decided that we can try to implement it using xcop since it produces quite strong structure of xml

[levBagryansky]

@yegor256 Such tests have one significant advantage: they clearly show how xsl transformation works.

[maxonfjvipon]

@levBagryansky thanks for your contribution, but the final decision is that such testing is a bad idea

[levBagryansky]

@maxonfjvipon ohh, ok