Design polishing of App Navigation

[georgehrke]

• The "Shared" icon with text is closer to the 3-dot icon than the share icon, why that?
  Label was removed, doesn't apply anymore
• The "Contact birthdays" calendar, being a default calendar, needs a color that is better visible and fits with the others? The one you use for "Default calendar" in the screenshot would fit.

[georgehrke]

The "Contact birthdays" calendar, being a default calendar, needs a color that is better visible and fits with the others? The one you use for "Default calendar" in the screenshot would fit.

Opened PR in server: nextcloud/server#18895