Get power factor from CSE7761, enable zero cross detection and allow calibration for measurements

**Describe the problem you have/What new integration you would like**

I think it would be nice to get power factor from the CSE7761, as well as enable zero-cross detection for relay switching (if really relevant...), and to allow calibration for sensors.
I don't know ho to modify / test code to transfer Tasmota code to esphome (https://github.com/arendst/Tasmota/blob/development/tasmota/tasmota_xnrg_energy/xnrg_19_cse7761.ino).

**Please describe your use case for this integration and alternatives you've tried:**

I must stay to Tasmota if I want to use these features..

**Additional context**

Start by reading Tasmota's tasmota/tasmota_xnrg_energy/xnrg_19_cse7761.ino, which the issue links, and compare its CSE7761 behavior with the corresponding ESPHome integration entry point. Done would require a decided scope and working support for power-factor readings, zero-cross detection for relay switching, and sensor calibration.

Written by the indexing model from the issue text.