Refactor some ext/pcre code for performance (#12447)

* Always inline populate_match_value and fix argument type

The call overhead of this function is quite large.

* Use _new variant of zend_hash in some places to avoid additional check

* Move allocation of match_sets down to simplify and reduce code size

* Move pcre2_get_ovector_pointer out of the loop

This is allocated together with the match data and stays loop invariant:
the pointer is always the same (the values not however).

* Mark error condition as cold block

* Simplify condition: subpats is already checked

* Move array size preallocation to use allocate the up-to-date size

* Simplify condition

* Rework internal functions to avoid repeated unwrapping

* Remember Z_ARRVAL_P(return_value)

The lookup is loop invariant.

* Mark some pointers as const

Author: nielsdos