platform: Add USB device MaxPower default setting

Set the USB descriptor strings. I accepts UTF-8 strings with
codepoints up to 16 bit.

  void setup() {
    USBDevice.setManufacturer("MyManufacturer");
    USBDevice.setProduct("MyProduct");
  }

Huge USB configurations might need more than 256 bytes for the
config descriptor buffer. MIDI devices with 16 virtual ports
grow the descriptor to 600+ bytes.

This call replaces the built-in buffer with the supllied buffer. The
call copies the content of the old buffer to the new buffer:

  uint8_t buf[1024];
  USBDevice.setDescriptorBuffer(buf, sizeof(buf));

TC6_CH0, TC6_CH1, TC7_CH0, TC7_CH1 on SAMD21J
TCC0_CH6, TCC0_CH7, TCC1_CH4, TCC1_CH5, TCC1_CH6, TCC1_CH7, TC6_CH0, TC6_CH1, TC7_CH0, TC7_CH1 on SAMD51J

Enable TC6 & TC7 for __SAMD21J18A__

Added Additonal Timers

tinyusb: Allow to replace the built-in descriptor buffer

tinyusb: Allow to set the USB manufacturer/product identifiers

add Descriptor to setManufacturer/setProduct

follow up to pr #172

This allows to compose the descriptor programmatically. The calling code
can compose a MIDI descriptor with up to 16 virtual wires/jacks at
initialization time.

Tested with the tinyusb -> MIDI -> midi_test example. This commit should
not change any behavior, future extensions of the calling MIDI device
will make use of it.

New boards could have DAC0 & DAC1 on different pins. DAC0 & DAC1 pins are defined on each variant.h file, so it is not needed to reference to pins A0 & A1. With this change the code is more generic. Changes affect to analogWrite & analogRead functions.

Change references from A0 & A1 to DAC0 & DAC1

tinyusb: MIDI - split descriptor initializer into individual sections

…r stuff! (servo is TC1)

allow PDM mic on pybadge edge
change pyportal backlight timer

…lers

SPI clock freq previously clipped at MAX_SPI/2 (6 MHz) rather than MAX_SPI. Now works correctly.
Additionally, MAX_SPI set at 24 MHz on SAMD21. This is only slightly beyond spec and so far seems reliable with SD and SdFat tests on M0 Adalogger, eyes on HalloWing M0.

SAMD21: Fix freq clipping in SPI.h, allow 24 MHz SPI

This fixes strcpy_uni16() to return the correct number of characters.
It wasn't visible in the host so far, because the strings have been NUL
terminated.

tinyusb: Correct descriptor string length calculation

…iptor()

refactor tinyusb core

update tinyusb

tinyusb core: improve setup handling

improve tinyusb samd driver

revert 6630fe7 availableForWrite() return int

Add action ci to build examples in libraries folder that comes with BSP

…4lf_math.a

Added extra space to force rerun of CI

Force linker to use newer Arduino-provided versions of libarm_cortexM4lf_math.a

For safety, this fix also validates that, if
`LITTLE_ENDIAN` was already defined, that it
was defined to have the same value that the
code sets this to.

The compiler found this, not me.  Building with
all warnings enabled is recommended.

Fix compile warnings