The master_clock_pin was already optional, but not specifying it would
result in a crash. This fixes it, so it really can be omitted, when the
camera module has its own clock source built in.
This uses the esp32-camera code instead of our own homebrewed camera code.
In theory it supports esp32, esp32-s2 and esp32-s3, as long as they have
PSRAM.
This is very basic and doesn't support changing any camera parameters,
including switching resolution or pixelformat.
This is tested on the Kaluga (ESP32-S2) and ESP32-S3-Eye boards.
First, reserve some PSRAM by putting this line in `CIRCUITPY/_env`:
```
CIRCUITPY_RESERVED_PSRAM=524288
```
and hard-reset the board for it to take effect.
Now, the following script will take a very low-resolution jpeg file and print
it in the REPL in escape coded form:
```python
import board
import esp32_camera
c = esp32_camera.Camera(
data_pins=board.CAMERA_DATA,
external_clock_pin=board.CAMERA_XCLK,
pixel_clock_pin=board.CAMERA_PCLK,
vsync_pin=board.CAMERA_VSYNC,
href_pin=board.CAMERA_HREF,
pixel_format=esp32_camera.PixelFormat.JPEG,
i2c=board.I2C(),
external_clock_frequency=20_000_000)
m = c.take()
if m is not None:
print(bytes(m))
```
Then on desktop open a python repl and run something like
```python
>>> with open("my.jpg", "wb") as f: f.write(<BIG PASTE FROM REPL>)
```
and open my.jpg in a viewer.
