Add Persistence notification flags

[3v1n0]

FDO Notifications had persistence flags, we don't support them in the portal, but applications may want to be able to still use them.

While transient notifications can be shown as they are, resident ones could instead be bothering an user, so add a further permission check in such case.

[3v1n0]

I wanted to add permission tests, but sadly this is a bit complex at the moment because of the xdp_app_info_is_host checks (which basically avoid any permission check).

So, I thought about defining a XDP_APP_INFO_KIND_TEST app that somewhat works, but requires further tests changes.

So, any suggestion here?

[3v1n0]

@GeorgesStavracas hey, could you have a look at this?

And #791 maybe :-)

[3v1n0]

So, I thought about defining a XDP_APP_INFO_KIND_TEST app that somewhat works, but requires further tests changes.

So, the paradigm to make things more testable is in #904, so once that lands this will be easily testable.

[swick]

@3v1n0 is this still relevant with the Notifications v2 portal landing soon?

[jsparber]

I think this can be closed since notification v2 has a new property display-hint which does the same thing as proposed here. See: #1298

[GeorgesStavracas]

Thanks @jsparber for checking this. @3v1n0 as always feel free to reopen if you think this still applies!