feat(mpd): add playing-interval option

[theoratkin]

As described in #4325, the default 1-second timer for the Playing state is very noticeable when running MPD server on localhost. This pull request adds a playing-interval option to the mpd module which allows configuring this interval (in milliseconds). Defaults to 1000 milliseconds.

Closes #4325.

[Alexays]

Could you add this new option to the man 🙏

[theoratkin]

@Alexays done!

[theoratkin]

Hey @Alexays, is there anything else blocking this from being merged? I'd love to continue using the official package instead of my fork :slightly_smiling_face: Let me know if you need me to squash the commits or do anything else.