The web app should get state from the robot when loaded

[amalnanavati]

Currently, the web app persists its state for 1 hour. The intent of that was that if the robot arm is in some configuration, and then say the WiFi dies or the user's device resets or such, the robot arm hasn't moved, so when the user re-opens the web app it should stay in the same state.

However, what if the arm did move? (e.g., a caregiver turned the robot off and on and re-homed it? Or in sim mock where the robot state resets when you restart MoveIt?) To address this, when the web app first opens, it should attempt to get the state from the robot (e.g., there should be a a service that gets the robot arm configuration and extrapolates and returns which state the robot must be in). If that service fails, then the web app can persist state.

Thanks @jjaime2 for raising this!