## Summary
Remove the dead "New Message" notification channel.
This channel was used for a tiny period, probably around 4 years ago, when we thought the only way to support sending MMS on Android was to be the default SMS app, thus we wanted to show users a notification when they received messages while our app was in charge of handling them.
Thankfully, we do not need to be the default SMS app, so this notification channel should be removed.
## Test Plan
### Before:
Looking at the list of notification streams in the settings for KDE Connect will include a "New Message" channel. Notifications are never posted to this channel.
### After:
Users will not see a "New Message" channel. Note that it does show a count of deleted streams, to prevent spam. See [documentation](https://developer.android.com/develop/ui/views/notifications/channels#DeleteChannel) for explanation.
Starting next month (September 2023) it will be required to target
Android 13 to publish to the Play Store.
On Android 13, we need to request the POST_NOTIFICATIONS permission.
This change adds the permission as required/optional to the plugins
that do create notifications. It also adds a popup to request it the
first time you open the app.
Fixes a race condition where onNetworkChange was called before the new
network became the default and the identity packet would be broadcast to
the wrong (e.g. cellular) network.
Allows navigating the app using the arrow keys on a keyboard or the
D-pad on a TV remote, up until the plugin list (I haven't checked
specific plugins).
Uses Android's `NsdManager` to announce a `_kdeconnect._udp` service using MDNS. This is done in addition to sending UDP broadcasts.
When we detect a device this way, we send a UDP identity packet to it (identical to the ones we broadcast but sent to a single device).
I also added a toggle in settings to disable the UDP broadcasts, so we can test MDNS by itself.
The Presenter activity including its layout file and related Java class were replaced with Compose UI.
Additionally, the androidx.compose.material3:material3 was updated from version 1.1.0 to version 1.1.1.
