feat: redesign login process (#1246)

* feat: first draft of login flow class

Based on https://github.com/nextcloud/neon/blob/be9492913f8e0fac9ebd790bee297678a3193df1/packages/neon_framework/lib/src/blocs/login_flow.dart#L64

* feat: design first login page

* feat: log in to nc.saber

* feat: add user agent string

* feat: log in with 3rd party nc

* feat: add extra step for enc keys

* fix: add `Prefs.loggedIn` getter

* fix: don't sync until logged in

* feat: ui for the enc password page

* feat: accept and check enc password

* feat: get username and pfp

* fix: accept bad certificates with pref

* fix: allow empty url

* chore: fix lints

* feat: update messages at top of settings

* feat: beginning of the new profile page

* feat: add quota to profile page

* feat: add quick links to profile page

* feat: logout

* feat: add faq to profile page

* feat: privacy policy and https prefix

* chore: delete LoginInputGroup

* chore: delete old profile page

* feat: save whether we have an app password

* i18n: remove unused strings

* feat: update faq for encryption password

* ref: make new strings translatable

* fix: update settings page when enc password entered

* ref: remove unused exception

* ref: shorten user agent

* chore: make dart scripts executable

* i18n: auto translations

* fix(i18n): remove extra faq items

* fix(i18n): mispellings of Saber