feat: domparser - ability to write more advanced expressions

[michalsn]

Description
The DomParser class is great for simple expressions, but if we want to check something more complicated, it unfortunately doesn't give us that option.

Therefore, this PR adds the ability to write an expression that will be executed directly by the DOMXPath class.
This way we can handle more advanced scenarios, like searching for nested elements in the DOM.

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[michalsn]

Not sure why, but unrelated to this PR checks fail.

[kenjis]

@michalsn This is an enhancement. Please change the base branch to 4.5.

[michalsn]

@kenjis Done.