Pool and lazily initialize fast args objects

[AnsisMalins]

Second attempt at achieving zero unsolicited allocations in fast args. First attempt: #685

[smokeelow]

hm, looks like something i need for my use case

i'm working on e-commerce framework with scripting capabilities via ClearScript and i see extreme memory leaks when scripts executed under high load

unmanaged memory grows to infinity with each execution ( i use FastProxy way)