Resolve battery and sensor values asynchronously after render

[raranguren]

Adds an optional resolve?: () => Promise<string> on FingerprintData: tiles render a placeholder, then a single post-render loop in main.ts resolves each one and updates it in place. Adding a new async value is just attaching a resolve.

Github page (temporary for testing): live demo

Testing before submitting:

• Desktop Chrome: battery fills in (was "Loading..." and not implemented)
• Firefox: battery shows "not supported" as before
• Mobile: sensors resolve (Accelerometer / Gyroscope / Magnetometer)