extract rtc module, extract tank module, fix backupview refresh, switch to embedded storage for eeprom

rust/src/tank.rs

@@ -1,4 +1,5 @@
 use crate::{config::TankConfig, hal::HAL};
+use anyhow::Context;
 use serde::Serialize;
 
 const OPEN_TANK_VOLTAGE: f32 = 3.0;
@@ -151,7 +152,12 @@ impl TankState {
 
 pub fn determine_tank_state(board: &mut std::sync::MutexGuard<'_, HAL<'_>>) -> TankState {
     if board.board_hal.get_config().tank.tank_sensor_enabled {
-        match board.board_hal.tank_sensor_voltage() {
+        match board
+            .board_hal
+            .get_tank_sensor()
+            .context("no sensor")
+            .and_then(|f| f.tank_sensor_voltage())
+        {
             Ok(raw_sensor_value_mv) => TankState::Present(raw_sensor_value_mv),
             Err(err) => TankState::Error(TankError::BoardError(err.to_string())),
         }