* Removes two account copy steps from InstructionProcessor::native_invoke().
* Moves gathering of keyed_accounts, caller_write_privileges and program_indices into InstructionProcessor::create_message().
* Explicitly routes the serialized account lengths to enable sharing of existing account structures.
* Recycles existing account structs in CPI syscall.
* Moves syscall_registry into the rbpf Executable constructor.
* Adds the reject_unresolved_syscalls flag which is only set when deploying programs via the CLI.
* Add rbpf-cli tool
* Replace explicit file type specification by required positional arg
- the type of file is determined automatically. If ELF magic found,
the program file is considered to be an executable ELF file, and
an assembly input file otherwise.
* Add a note about tool's limitations and input format description