[ReadOnlyPropertyRector] Add failing test for cloned properties

[internalsystemerror]

Adds failing test for rectorphp/rector#6898.

Fixing this appears not to be a simple task (esp for a rector noob like myself) as I'm unsure how this is managing to figure out whether a property is written to or not.

If someone else wants to take over this PR, feel free. In the meantime I will continue to try to fix, if only for my own education purposes, but I don't want that to get in the way of this issue being resolved.

[internalsystemerror]

My current working theory is that this line

rector-src/src/PhpParser/NodeFinder/PropertyFetchFinder.php

Line 151 in 068369e

if (! $this->nodeNameResolver->isName($propertyFetch->var, self::THIS)) {

is preventing the clone from being included in the list of property fetches.

[internalsystemerror]

I'm attempting to try and check if the type of the variable is the same as the declaring class (instead of just checking if the variable name is this). However, I'm at a complete loss as to how I can check the type of the variable.

I would be grateful for any insights here as I think I've reached my limit from just reading code.

[samsonasik]

@internalsystemerror I cherry-picked your commit at PR #1599