Lifetime cost and potential sensors

[knudsvik]

** TESTS **

• [ ] Lifetime cost sets up auto from yaml
• [ ] Lifetime cost sets up auto from configFlow
• [ ] Lifetime cost restores state
• [ ] Lifetime cost inherits unit of measurement
• [ ] Lifetime potential sets up auto from yaml
• [ ] Lifetime potential sets up auto from configFlow
• [ ] Lifetime potential restores state
• [ ] Lifetime potential inherits unit of measurement