feat: allow updating pin metadata

[achingbrain]

Adds a setMetadata method to the pins interface to allow updating pin metadata, also a .get method to retrieve data for a specific pin.

Change checklist

• [x] I have performed a self-review of my own code
• [x] I have made corresponding changes to the documentation if necessary (this includes comments as well)
• [x] I have added tests that prove my fix is effective or that my feature works