#109 implemented, cleanup and small fixes

src/consents/migrations/0004_userconsents_active.py

src/consents/models.py

src/consents/urls.py

src/consents/views.py

src/frontend/src/app/app-routing.module.ts

src/frontend/src/app/app.module.ts

...management/consent-history/consent-history.component.html

...management/consent-history/consent-history.component.scss

...agement/consent-history/consent-history.component.spec.ts

...t-management/consent-history/consent-history.component.ts

...frontend/src/app/consent-management/consentDeclaration.ts

...agement/provider-settings/provider-setting.component.html

...anagement/provider-settings/provider-setting.component.ts

src/frontend/src/app/navigation/header/header.component.html

src/frontend/src/app/navigation/header/header.component.ts

src/frontend/src/app/services/api.service.ts

src/frontend/src/environments/environment.prod.ts

src/frontend/src/environments/environment.ts

src/frontend/src/favicon.ico

src/frontend/src/locale/messages.de.xlf