Add CS5460A power-meter component

[balrog-kun]

Description:

CS5460A is a chip that calculates power, RMS current, voltage, energy
etc. and communicates over SPI. Easy to buy on a breakout board.

Pull request in esphome-docs with documentation (if applicable): esphome/esphome-docs#944

Checklist:

• The code change is tested and works locally.
• [kinda] Tests have been added to verify that the new code works (under tests/ folder).

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in esphome-docs.

[balrog-kun]

Ok, thanks @glmnet. Doing all the work in set_timeout() callbacks now, loop() is empty and everything works.

After each measurement we schedule STATUS register reads (through SPI) at 0.8x the expected time left until next reading but not less than 30ms. So for example when we expect a new data at T + 1 second, we do an SPI read at:
T + 800ms
T + 960ms
T + 992ms
and then every 30ms until data ready or until 500ms have passed.

Also added runtime reset logic for when the device gets stuck for 15s, and added the usage of status_momentary_warning() on non-fatal errors.

[balrog-kun]

Rebased on esphome/dev, added default device_class params to the sensor_schema() usages and added the CODEOWNERS tag.