getOrPut variants return this structure, with pointers
to the backing store and a flag to indicate whether an
existing entry was found.
Modifying the key is allowed only if it does not change the hash.
Modifying the value is allowed.
Entry pointers become invalid whenever this ArrayHashMap is modified,
unless ensureTotalCapacity/ensureUnusedCapacity was previously used.
key_ptr: *Kvalue_ptr: *Vfound_existing: boolindex: usizepub const GetOrPutResult = struct {
key_ptr: *K,
value_ptr: *V,
found_existing: bool,
index: usize,
}