* Makes members of SyscallContext public.
Removes check_aligned and check_size from SyscallContext.
* Replaces InvokeContext::set_syscall_context() in tests with mock_create_vm!().
* Passes SyscallContext directly to InvokeContext::set_syscall_context().
* Merges TraceLogStackFrame into SyscallContext.
* Removes the create_vm!() macro.
* Moves BpfAllocator from bpf_loader into program_runtime.
* Frees BpfAllocator from Rc<RefCell<>>.
* Removes unused code from BpfAllocator.
* Consume CUs for heap before doing the allocation.
* Exposes syscalls in rbpf-cli.
* Adds debugging_features parameter to load_program_from_bytes() and load_program_from_account().
* Removes test_bpf_loader_non_terminating_program() as that is already tested in RBPF.
* Moves stack and heap allocation back onto the program runtime stack.