sout: pass ES string ID to `pf_add`

The new ES string ID was added initially in the core for playback scenario allowing the user to have a readable and guaranteed unique representation of each ES.

Introducing it in stream output will allow users to specify ESes to stream out filters with more precision than with legacy ES ID. ES ID has the disadvantage to only be unique per demux, hence, a multiple demux scenario often provided multiple ES with the same ID. Strings ID are guaranteed to be unique, regardless of the number of demuxes the input manages.

The duplicate stream out filter will be handled in a separated MR as I took the opportunity to refactor some things in it. You can have a look here, it will be submitted quickly after this MR