Add support for skip and rewind 15 seconds

[lineville]

Feature Purpose

It would be nice to add two new commands to the toolbar for skipping ahead 15 seconds or rewinding 15 seconds, similar to the interface in the Spotify desktop app. These quick seek commands are particularly handy when listening to podcasts to easily skip through ad breaks 😄. I'd be happy to contribute these enhancements 🙇

Proposed Changes

• Add a new command named Skip Forward that wraps the seek Seek To command and just seeks to 15 seconds ahead of the current time.
• Add a new command named Skip Back that wraps the seek Seek To command and just seeks to 15 seconds before of the current time.
• Add new button on the right end of the status bar buttons to invoke the skip ahead command.
• Add new button on the left end of the status bar buttons to invoke the skip back command.

[lineville]

@ShyykoSerhiy I'm curious if this project is still active and accepting contributions?

[lineville]

Hope you don't mind if I publish a fork of this, I'll be sure to give credit and link to this project though ❤