Add Stat based on MLST command

[panthony]

This PR expose the MLST command that allows returning the metadata of a file without relying on a list.

The returned msg has the following format:

C> MLST
S> 250-Begin
S>  type=dir;unique=AQkAAAAAAAABCAAA; /
S> 250 End.

https://datatracker.ietf.org/doc/html/rfc3659#section-7.7.5

I was not sure how to handles the "begin/end", it looks like in "List" it is ignored because it fails the parsing.

There is a slight difference with MLSD apparently because the file content is prefixed by a whitespace.

The idea for this function is to be used in findItem when supported to avoid an unnecessary listing to retrieve an item which I'm currently trying to implement.

Sorry for the lack of test there was nothing bootstrapped to add a test easily