This patch modifies `Connect` api.

Now, to connect to the Tarantool, you need to pass an
object that satisfies `tarantool.Dialer` interface.

You can use one of the existing implementations:
`NetDialer` or `OpenSslDialer`.

For example:
```
conn, err := tarantool.Connect(context.Background(), tarantool.NetDialer{
	Address:  "127.0.0.1:3301",
	User:     "user",
	Password: "secret",
}, tarantool.Opts{})
```

To create a connection pool, you need to pass a `map[string]tarantool.Dialer`,
where each dialer is associated with a unique ID (for example, it can be
the server address). Dialers will be distinguished from each other using
these IDs.

For example:
```
connPool, err := pool.Connect(context.Background(), map[string]tarantool.Dialer{
	"127.0.0.1": tarantool.NetDialer{
		Address:  "127.0.0.1",
		User:     "user",
		Password: "secret",
	},
}, tarantool.Opts{})
```

The `conn.RemoteAddr` and `conn.LocalAddr` functions have been removed.
To obtain the connection address, you can use `conn.Addr`.

Now, `NewWatcher` checks the actual features of the server, rather than relying
on the features provided by the user during connection creation.

In the case of connection pool, watchers are created for connections that support
this feature.

`ClientProtocolInfo`, `ServerProtocolInfo` were removed. Now, there is `ProtocolInfo`,
which returns the server protocol info.

`pool.GetPoolInfo` was renamed to `pool.GetInfo`. Return type changed to
`map[string]ConnectionInfo`.

Part of #321

Closes #321