Updated NotificationHelper to use highest notification priority (PRIORITY_MAX)

[jomapp]

We should ensure that notifications always have the highest priority also on older devices.
Resolves #202

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Description

[timbrueggenthies]

To use the high priority, it is also needed to adjust this setting on the NotificationChannel on Devices >= API 26 (see here)

[jomapp]

To use the high priority, it is also needed to adjust this setting on the NotificationChannel on Devices >= API 26 (see here)

For the NotificationChannel the current setting ("IMPORTANCE_HIGH") is already the highest. The Google documentation specifies "unused" for "IMPORTANCE_MAX". (see here)

[timbrueggenthies]

Okey, didn't knew that. Thanks for pointing out! 👍

[jomapp]

Okey, didn't knew that. Thanks for pointing out! 👍

Sure :) Was also quite surprised seeing that "IMPORTANCE_MAX" is not used anymore.

[htooisap]

@jomapp thank you for your contribution this. As you already correctly noted, we are using PRIORITY_HIGH because PRIORITY_MAX is not in used.

[jomapp]

@jomapp thank you for your contribution this. As you already correctly noted, we are using PRIORITY_HIGH because PRIORITY_MAX is not in used.

You're welcome but it's different from what you wrote. We should change it to PRIORITY_MAX.

In the project we are currently using IMPORTANCE_HIGH, for the NotificationChannel, which is fine (since IMPORTANCE_MAX is unused.) But for the notification itself we should use PRIORITY_MAX instead of PRIORITY_HIGH since for older devices below API 26 this ensures that notifications are also shown with the highest priority.

Infact: IMPORTANCE_HIGH (>= API 26) == PRIORITY_MAX (< API 26)

[jomapp]

@HeeTattSap Can we reopen this PR? I think it's relevant (please see my last comment) Thank you!

[htooisap]

@jomapp thank you. I misunderstood that this was about the channel.

Your fix works and I have validated this on Android 6 and Android 10 devices. We will merge this change. Thank you again for your contribution :)

[jomapp]

@HeeTattSap thanks! No worries, thank you for merging it :)