This changes all SPI functions that take data pointers which are
not modified so that the declaration is const. This allows them
to be used with const data (i.e. held in flash). No functional
changes are required.

The defnitions of spiWrite() and spiTransferBytes()  in
esp-hal-spi.h/c have been updated to be consistent.

Tests:
 - Build a simple sketch using SPI.writePattern() and
   SPI.transferBytes()  which uses const data and verify that the
   attached device functions as expected.

* Add APB change callbacks and move cpu code to own file

* Properly set esp_timer and FreeRTOS tick dividers

* Improve updated devisors

* No need to update REF_TICK yet

* Add initial handling for UART baud change

* fix uartWriteBuf and uartDetectBaudrate

* trigger callbacks even when APB did not change

* toggle UART ISR on CPU change

* add XTAL freq getter and add cpu freq validation

* Support CPU frequency changes in I2C (#2287)

**esp32-hal-i2c.c**
* add callback for cpu frequency changes
* adjust fifo thresholds based on cpu frequency and i2c bus frequency
* reduce i2c bus frequency if differential is too small
**Wire.h**
* version to 1.1.0

* Implement clock change for the other peripherals

* remove bad CPU clock values from the menu

* Add note to CPU freqs that support WiFi and BT

* Add support to HAL for APB frequencies different than 80MHz

* Add support for CPU frequencies in the IDE board menu

* Switch to fast set_config

* Add method to uart so debug can be reassigned after apb frequency switch

* Return real APB frequency

Fixes #1094

Fixes: https://github.com/espressif/arduino-esp32/issues/640

Related: https://github.com/espressif/arduino-esp32/issues/634

It appears that the configurations for `ck_out_edge` were inverted for `SPI_MODE2` and `SPI_MODE3`. You can check the technical reference manual on page 76, table 23 "Clock Polarity and Phase, and Corresponding SPI Register Values for SPI Master".

I've check with my oscilloscope that the current configuration is wrong and this fix corrects the issue.

Use transactions to skip mutex locks for reads and writes

IDF Options:
- Autostart Arduino (implements app_main)
- Disable HAL locks
- Set HAL debug level
- Auto-connect STA if configured (else will connect after WiFi.begin())