Refactor - vm interface of `BuiltinFunction`s

[Lichtso]

This drastically simplifies the vm interface of BuiltinFunctions so that it becomes a lot closer to the vm internal call interface:

• Instead of passing ContextObject, MemoryMapping and ProgramResult the encrypted pointer to the entire EbpfVm is passed, which is then decrypted and decomposed inside declare_builtin_function(). Thanks to #534, this does not even require swapping of argument registers.
• The instruction metering around syscalls from the interpreter and JIT was moved into declare_builtin_function(), which does not only deduplicate the logic, but also allows LLVM to optimize the register allocation, spilling and perform inlining, effectively reducing the cost of a syscall from three context switches between the VM and Rust ABI, down to one.

Unfortunately, encrypt_runtime_environment is now no longer optional as we can not read the config of the VM without dereferencing the potentially encrypted VM pointer.

[codecov-commenter]

Codecov Report

Merging #535 (b4391ac) into main (b1b50f7) will decrease coverage by 0.16%. The diff coverage is 95.08%.

@@            Coverage Diff             @@
##             main     #535      +/-   ##
==========================================
- Coverage   89.70%   89.55%   -0.16%     
==========================================
  Files          24       24              
  Lines       10213    10094     -119     
==========================================
- Hits         9162     9040     -122     
- Misses       1051     1054       +3     

Files	Coverage Δ
src/interpreter.rs	98.81% <100.00%> (-0.03%)	:arrow_down:
src/jit.rs	91.49% <100.00%> (-0.49%)	:arrow_down:
src/vm.rs	85.90% <100.00%> (+0.06%)	:arrow_up:
src/program.rs	80.58% <90.90%> (+2.50%)	:arrow_up:

... and 1 file with indirect coverage changes