Selectively remove matched style/attr

[strarsis]

This PR adds options to removeMatchedSelectors option for selectively removing style and/or attr.
This can be useful if the attrs should be kept for selecting or styling with pseudo-classes (e.g. :hover).

[TrySound]

Hi @strarsis. I don't get what "attr" does here. Is this still relevant?

[strarsis]

@TrySound: This PR adds optional sub-options to the removeMatchedSelectors option which allow finer control:
Should styles be kept after inlining?
Should attributes (id or class currently) be removed after the matching styles have been applied?
Especially the second option can be useful, e.g. styling parts of a SVG using its classes after inlining the styles.

[SethFalco]

This shouldn't be necessary anymore.

The problem this is solving has been address by:

• feat(inlineStyles): remove redundant presentation attrs #1829
• fix(inlineStyles): dont remove wrapper class if traversed #1832
• fix(inlineStyles): dont remove id if traversed in another selector #1836

TL;DR: Added a helper includesAttrSelector, which checks if an ID/class/attribute it used by a CSS selector. If so, we won't remove it.

Feel free to share an SVG if you can still reproduce scenarios where we're removing attributes too eagerly. However, in theory it should be possible for us to even drop the removeMatchedSelectors option entirely now I think. 🤔