[Feature Request] change pitch and speed

**Is your feature request related to a problem? Please describe.**
no

**Describe the solution you'd like**
2 new commands that can change the pitch and the speed of a requested song

**Describe the basic flow/steps of using this feature**
the user says the command "speed 2" or "pitch 2"
the song would be twice as fast or twice as high pitched

**Additional context**
no

**Have you confirmed that this idea is not already described here?**
https://github.com/jagrosh/MusicBot/projects/1
i didn't find an idea like this

The issue names no files, tests, or entry points; start by tracing how MusicBot handles the `speed` and `pitch` commands and applies changes to a requested song. Done means both commands accept the proposed numeric factor and produce the specified speed or pitch result, with coverage for their behavior; an open linked pull request indicates work is already underway.

Written by the indexing model from the issue text.