ZJIT: Specialize invokeblock for ISEQ

[k0kubun]

We specialize only ifunc invokeblock right now. We should specialize ISEQ invokeblock.

[tekknolagi]

If we can do this by manually doing a frame push and jumping, like SendDirect, that would be ideal. Then also @nirvdrum can copy this special frame push for inliner

[k0kubun]

Yeah it's supposed to be a regular JIT-to-JIT call.