624 permissions enhancements 2

[MariusDoe]

Closes #624.

• [x] Warning for public user permissions change (65286c38b8f187f455fed044e01de8fef6bdf52e)
• [x] Tooltips for permissions (535274f28d1ef15de73c96502f9f52cc67b39608)
• [x] Tooltip for system section (535274f28d1ef15de73c96502f9f52cc67b39608)
• [x] UsersView: "Nutzerverwaltung" -> "Nutzer- und Rechteverwaltung" (ddf9eb995961dd5281a006ce98655b717f367cfb)
• [x] "Kommentar anpinnen" -> "Kommentar fixieren" (fcddccb341a7ffbf823a013032293b7a723ecdce)
• [x] Improve "invalid forgot-password link" error message (8155c81e078d095531d8cf09a7766e2d15d6bfe8)
• [x] Show password requirements in change/reset password views (b445d962b7e02b801e31472895eccb37091e3227)

[olschulz]

immer noch 🐘