Proposal: Adding SplFixedArray->push() and SplFixedArray->pop()

Hi Internals, Currently, PHP doesn't have a built in memory-efficient array type with convenient push, pop, and other operations, similar to a list/vector in other languages. The closest built in in SPL is [SplFixedArray](https://www.php.net/manual/en/class.splfixedarray.php) https://www.php.net/manual/en/class.splstack.php uses a doubly linked list, which uses much more memory and time than sequential memory. Contrary to the name and description in https://www.php.net/manual/en/class..splfixedarray.php, the class is already resizable. The resize method is setSize - https://www.php.net/manual/en/splfixedarray.setsize.php (increasing size is efficient - erealloc will extend the underlying array into free memory if there is nothing in the way) Many programming languages have a memory-efficient list/vector type that can be conveniently appended to and popped from. https://docs.python.org/3/tutorial/datastructures.html#more-on-lists https://www.cplusplus.com/reference/vector/vector/ https://docs.ruby-lang.org/en/2.0.0/Array.html#method-i-push Is there any interest in adding this? It would be much more efficient to add these in C. Thanks, - Tyson