The space after `&` made it look like the `&` was not part of the signature,
possibly leading to confusion why the two signatures are incompatible without
carefully reading the message.
Move more low-hanging fruit, creating new directories for the tests for:
* comparisons
* dynamic calls
* error messages
* `error_reporting()`
* exceptions
* `foreach()`
* garbage collection
* group `use` statements
* heredoc and nowdoc
* `goto` jumps
* late static binding
* magic methods
* namespaces
* numeric literal separators
* objects
* `settype()`
* cleaning of temporary values
* `unset()`
Additionally, move some tests into the existing subdirectory for `list()`
tests.
Drive-by fixes of some test numbers in the names of the `goto` tests.
Work towards GH-15631
