Release specific key in keyboard's HID report

[vishesh-varma]

Currently, there are 3 functions in Adafruit_USBD_HID.h file, which are:

• keyboardReport(uint8_t report_id, uint8_t modifier, uint8_t keycode[6]);
  Presses up to 6 keys + a modifier.
• keyboardPress(uint8_t report_id, char ch);
  Presses the specified character.
• keyboardRelease(uint8_t report_id);
  Releases all the keys currently pressed.

Since there is a function that presses one specific key, it makes sense to have a function that would only release the specified key, and not all of them.
The use case here is pretty apparent, when switching between different combinations of keys, one can only press the next combination after releasing the currently pressed one.