floss: avrcp: implement send_key method to handle the key event

Continue development for uinput library to support key event handling.
uinput will be responsible for translating the AVRCP key event into
uinput key press with the translation table and writing to uinput fd
to simulate a key press.

Implement the default method for UInputDev and UInputId to simplify the
initialization. Update the close process also to clear out the stored
device information.

Bug: 240780817
Tag: #floss
Test: verified locally that uinput device is created

Change-Id: I2bd9e78faa3fb8812e28f86a82db01ce3fe9561b