WIP: BLE HID

[sago35]

This PR adds support for BLE HID.

To make it work correctly, you need to change the max_len in github.com/funkycode/bluetooth's gatts_d.go to 144.

At least on Android 14, it seems to be working reasonably well.
It's not working on Windows.

Here's what is added in this PR:

Connect to the host using BLE HID.
Connect split keyboards to each other using BLE.

Please check the implementation examples below.
However, there is still a possibility of changes to the API, etc.

• Connect to the host using BLE HID.

  • tinygo-keyboard/targets/sgkey2/main.go

    Lines 75 to 81 in fde11c0

    	bk := ble.NewKeyboard(usb.Product)
    	err := bk.Connect()
    	if err != nil {
    	return err
    	}
    	d.Keyboard = bk

• Connect split keyboards to each other using BLE.

  • tinygo-keyboard/targets/sgkey2/main.go

    Lines 61 to 73 in fde11c0

    	d.AddBleSplitKeyboard(0x12, bluetooth.DefaultAdapter, "xiao-kb01-0.1.0", [][]keyboard.Keycode{
    	{
    	jp.KeyA, jp.KeyB, jp.KeyC, jp.KeyD,
    	jp.KeyE, jp.KeyF, jp.KeyG, jp.KeyH,
    	jp.KeyI, jp.KeyJ, jp.KeyK, jp.KeyL,
    	jp.KeyMediaVolumeDec, jp.KeyMediaVolumeInc,
    	jp.WheelDown, jp.WheelUp,
    	jp.MouseLeft, jp.MouseRight,
    	},
    	})

  • tinygo-keyboard/targets/xiao-kb012/main.go

    Lines 106 to 112 in fde11c0

    	bk := ble.NewSplitKeyboard(usb.Product)
    	err := bk.Connect()
    	if err != nil {
    	return err
    	}
    	d.Keyboard = bk

[sago35]

Media keys sometimes work, but sometimes they don't.
The mouse still doesn't work.
Layer keys (KeyModX and KeyTo) are working.

[sago35]

I have created a rebased version on the latest origin/main using the patched version of tinygo.org/x/bluetooth mentioned in #48. I will close this PR.