Improvements of pulse_counter component

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

The pulse_counter component is lagging some features for my use case, that I also can't reproduce otherwise.
These are the features that I have in mind:
* Implement a 'slow' mode for ESP32 where it behaves like an ESP8266
* Implement an option to send an MQTT message with the time in ms every time an impulse is detected.
* Alternatively send the count every given interval and a retaining zero after the first interval no impulse is detected.

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

I have 12 S0 meters (10*Power and 2*Water-flow) for monitoring in my flat connected to an ESP32. [Wikipedia S0 (German)](https://de.wikipedia.org/wiki/S0-Schnittstelle) An S0 signal is just a 20 ms pulse every time a certain amount of energy, or water was used. I have a theoretic maximum of 3 pulses per second, but this would translate to a power consumption of 16A an all 3 phases (1imp/Wh).
The pulse_counter component on ESP32 only allows me to monitor 8 inputs.
~~I also would prefer to send the time in ms via MQTT each time a pulse was detected, or the count per second if there have been pulses and a retaining 0 in the first second no pulse was detected. This would lead to much fewer messages.~~ -> can be done with deltas
Re-building the pulse_counter component by using only binary_sensor-gpio components could work somehow, but is rather tricky.

**Additional context**

I like to start here a discussion on an update of the pulse_counter component and agree on the changes to be implemented.
I am willed to do the update myself and create a pull request, once it is agreed how to implement the new features.