feat: a hack for debugging via picodata tarantool

Run `picodata tarantool -i` in the instance directory of an instance
which you want to safely inspect. Run this in the console:
```lua
box.cfg()
require 'ffi'
ffi.cdef [[ int pico_internal_initialize_dummy(); ]]
ffi.C.pico_internal_initialize_dummy()
```

Now you have the `pico` global table available with some things you may
find useful, like `pico.raft_log()`.