Fix esp32 hardware timer performance

[mikee47]

This PR fix poor performance of hwtimer2 on ESP32 by using hardware directly.
It also fixes code so it can be used from C.

How many loop iterations can we achieve in 100 ms ?

ESP32

Using millis(), managed 105418 iterations, average loop time = 949ns (152 CPU cycles)
Using micros(), managed 102942 iterations, average loop time = 971ns (155 CPU cycles)

Using PolledTimer:
BEFORE: managed 135827 iterations, average loop time = 736ns (118 CPU cycles)
AFTER: managed 921085 iterations, average loop time = 109ns (17 CPU cycles)

ESP32C3

Using millis(), managed 98837 iterations, average loop time = 1012ns (162 CPU cycles)
Using micros(), managed 123863 iterations, average loop time = 807ns (129 CPU cycles)

Using PolledTimer:
BEFORE: managed 136670 iterations, average loop time = 732ns (117 CPU cycles)
AFTER: managed 551882 iterations, average loop time = 181ns (29 CPU cycles)

ESP32S2

Using millis(), managed 68260 iterations, average loop time = 1465ns (234 CPU cycles)
Using micros(), managed 68921 iterations, average loop time = 1451ns (232 CPU cycles)
Using PolledTimer:
AFTER: managed 528409 iterations, average loop time = 189ns (30 CPU cycles)