Support Gadgetbridge Canned Responses

[WhelanB]

I realised during development of the "reply" library that Gadgetbridge contains support for setting canned responses/replies directly through the app, which is preferable to customising via interface.html as it can support emojis/Unicode using text as bitmaps.

This PR consists of 2 main changes:

• Add a "disp(lay)" field to the replies.json file used by the reply lib. If display is set for a particular canned reply, it will be shown on the menu instead of the default "text" field, which is what is sent to Gadgetbridge as a response. This way, the "disp(lay)" field shown on the watch can contain image representations of emojis and other Unicode characters, while the reply to Gadgetbridge contains the raw Unicode bytes
• Expand the Android integration app to listen for a canned_responses_sync message, and write the data contained within that message to the replies.json file used by the reply lib. I'm planning to open an additional PR against Gadgetbridge on CodeBerg to send this message when canned responses are set:

[thyttan]

Changes to android integration app, calling @gfwilliams!

[gfwilliams]

Thanks! Nice idea about including emoji/etc.

I'm a bit concerned about the truncatedDisplayString being an array (see comment) but apart from that this looks good.

[gfwilliams]

Great, thanks!