Display mobile App loading screen instead of frontend's

[bgoncal]

To give more flexibility to the apps and also create a more native App experience, it would be nice if we remove the loading screen from the frontend and move it to the apps.
This would also help with the recent changes on android where the webview needs to manually provide the safe areas which causes a "jump" in the screen before the content is correctly positioned.

The idea is to have a channel in the external bus to show or hide the loader, below my initial proposal:

"loader/show"
"loader/hide"

CC: @bramkragten @TimoPtr

[bgoncal]

And the apps need to provide this variable to the frontend canDisplayNativeLoader: true

[TimoPtr]

old apps

[bgoncal]

@bramkragten I think the use cases as the same as when the frontend does right? The only difference is handling in the app instead.

[bramkragten]

We don't have functionality now to show the loading page after the app is loaded

[bgoncal]

In the app this can happen more often because we load the HA URL more than once for example when opening an specific page from a widget or any navigation that does not happen from the webview itself.

[bgoncal]

Something nice I just thought is, in the App if the loading does not finish (for some reason) we can present the option for the user to open app settings to check it's config, like after 5 seconds loading

[bramkragten]

We also have to keep error pages and database migration cases into account probably

[bgoncal]

Errors you mean that red text with a reload button below? How does the database migration looks like?