perf: reduce allocs when creating $_SERVER (#540)
* perf: reduce allocs when creating $_SERVER
* improve
* refactor: prevent C allocs when populating $_SERVER
* cs
* remove append()
* simplify
* wip
* cleanup
* add cache
* cleanup otter init
* some fixes
* cleanup
* test with a leak
* remove const?
* add const
* wip
* wip
* allocate dynamic variables in Go memory
* cleanup
* typo
* bump otter
* chore: bump deps
