Fix queue becomes null on disconnect

[ttongsul]

Attempt to fix #705, although I can't test it because reconnect() fails on my side.

[phatpaul]

FYI i tested this branch by doing this:

npm install VinardoZzZ2000/cordova-plugin-bluetoothle#fix/per-peripheral-queues --save
cordova plugin remove cordova-plugin-bluetoothle
cordova plugin add cordova-plugin-bluetoothle
cordova prepare android

I'm still having reconnect problems. If my BLE peripheral device disappears (out of range, or reboots), this plugin should try to reconnect to it. It does reconnect, but my JS code never gets a callback that it reconnected.

I suspect it is due to

cordova-plugin-bluetoothle/src/android/BluetoothLePlugin.java

Line 4089 in fa96bb4

connection = new HashMap<Object, Object>();

which clears the connection object when a disconnect happens.
Why do you clear it here? That means that a (automatic) reconnect will not trigger a callback to the JS code.
Instead, the callbacks should only be cleared after the close().

[ttongsul]

Hmmm, I didn't notice that, though that was already there before I made the changes. Does the working version not have that line?

[phatpaul]

Ok, I can't say that your additions broke the reconnect() functionality in this library. But they definitely seem broken.
This PR does not fix the reconnect after an explicit disconnect(). It also doesn't fix the automatic reconnect after the BLE device disappears/reappears.
So I'm not sure if this PR is useful.
I'll try to fix it in a separate PR.
Thanks for your help.

[ttongsul]

Sorry about that. I'll leave this PR here unless my PR that may have broke the functionality is reverted, or you made a working PR. Thanks.