Also, fix the code to pass the test:

1. Use `replace` instead of `insert` when appending entries. They may be
   overridden.
2. Increase pool worker queue size. Raft node may send several messages
   within a single tick. Without this change the second message is
   dropped.

The second change is a poorly designed workaround. Constant limit
doesn't seem to be both cost-effective and reliable at the same time,
but we don't have a better solution at the moment.

Close https://gitlab.com/picodata/picodata/picodata/-/issues/26

It makes testing easier. Monkey patching the handler isn't necessary
anymore. Instead, it's mocked now.

Follower makes a proposal. It's applied on both instances.

This patch also introduces a new API `picolib.raft_status`.

Close https://gitlab.com/picodata/picodata/picodata/-/issues/24

+ tarantool-sys submodule
+ tarantool-patches directory
+ build.rs build script to patch and build tarantool
+ static linking with tarantool
+ refactoring for cli arguments

The control flow of picodata looks as following:

Picodata binary -> exec tarantool -l picodata -> libpicodata.so -> ...

Since the libpicodata is a shared lib loaded by tarantool, we can't pass
it arguments as usual. At first, tarantool parses them by itself and
rejects uknown arguments. Secondly, it spoils argv array.

To overcome these two issues, this patch introduces argparse on behalf
of the picodata binary, and puts parsed values into the environment
variables.

P.S. Thihs is how command line args look from within libpicodata:

```console
$ tarantool -l picodata /dev/null --opt1 foo --opt2 bar
Hello from rust lib
arg[0] tarantool
arg[1] /dev/null
arg[2] --opt1
arg[3] foo
arg[4] --opt2
arg[5] bar
arg[6] --opt2
arg[7] bar
```

This patch introduces the new cargo package - picodata.

The package consists of two parts:
- The `picodata` binary does some env magic and executes
  `tarantool -l picodata`.
- The `libpicodata` dylib is the starting point for further
  development.