minSdk to 23

[bmarty]

Only <1% of the user from the PlayStore are using a device running API 21 (Android 5.0 and 5.1).

Let's consider moving minSdk value to 23.

Maybe create a first update to notify user on API 21 that this will be the latest upgrade.

Task (non-exaustive):

• Check fork agreement, especially Element's customers
• simplify the runtime permission handling
• Remove warning about Jitsi not supported on API 21

[jittygitty]

@bmarty Any huge advantage? I'm very skeptical of the supposed breakdowns and that 5.0 and 5.1 are truly less than 1% worldwide, I've seen no proof those metrics are all-inclusive of devices not running google play services. Oops sorry, I just noticed Jitsi not supported on API 21...

[bahur142]

Also consider dropping 6 and 7 in the near future. A lot of communication apps (popular and not so popular with millions of installs) supports 8 and above.