Escape double quote before sending command to MPD

[finnyb]

Pull Request Template

Description

Thanks for your contribution! Please include a summary of the feature or which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

Fixes # (issue)

Checklist:

• [x] follows style guidelines (run mvn spotless:apply to format the code)
• [x] commented my code in hard-to-understand areas
• [x] made corresponding changes to the documentation
• [x] validated static analysis
• [x] added tests that prove my fix or feature works