GPDR: Add Legal notice link and Privacy policy link when nextcloud is in maintenance mode

[cloud2018]

Is your feature request related to a problem? Please describe.
Due to the GPDR, a legal notice link and link to privacy statement are necessary.
At the login page legal notice link and link to privacy statement can be added, but if nextcloud is in maintenance mode, these links are not displayed.

Describe the solution you'd like
Also in maintenance mode, legal notice link and link to privacy policy should be displayed.
In addition, the individual slogan could also be displayed as well.

Additional context
Current page in maintenance mode without necessary links to legal notice and privacy statement:

[michag86]

I think it would be nice, if maintenance page is themed completely. The problem seems to be that no apps are loaded when maintenance mode is enabled. Maybe the theming app can create a static maintenance page on every theme change. And if such a static themed page exists, this is shown in maintenance mode.

cc @MorrisJobke

[MorrisJobke]

I think it would be nice, if maintenance page is themed completely. The problem seems to be that no apps are loaded when maintenance mode is enabled. Maybe the theming app can create a static maintenance page on every theme change. And if such a static themed page exists, this is shown in maintenance mode.

Completely different issue - this is about #5789

[joshtrichards]

Appears to have been addressed:

I think we can close this out.