Support multiple engines in one WASI Env

[syrusakbary]

Problem: right now running PHP with LLVM requires all the dependencies/subprocesses to be compiled with LLVM. Currently, when bash runs PHP (and bash is compiled with cranelift), the compilation fails (as is compiling PHP with Cranelift instead of LLVM).

This should not be required, we could run dependencies with other compilers, if artifacts are available