Merge branch '30-dashboard' into 'master'

Resolve "Dashboard"

See merge request AlekSIS/AlekSIS!100

Add dependencies from SchoolApps to pyproject.toml and update poetry.lock

See merge request AlekSIS/AlekSIS!107

Close "Check schoolapps requirements.txt and merge relevant dependencies into pyproject.toml" from #134

Resolve "Add verbose names for models"

Closes #144

See merge request AlekSIS/AlekSIS!105

Link activities and notifications to persons

See merge request AlekSIS/AlekSIS!98

(including, for the main AlekSIS module, trimmed history for
School-Apps code moved into separate AlekSIS äpps)

This references nonexistent files, so it’s preferable to remove
it now.

Reformat and add notifications a second time for showing new notifications in a special way

Resolve "Migrate missing templates to materialize"

Closes #125

See merge request AlekSIS/AlekSIS!104

# Conflicts:
#   aleksis/core/settings.py

Close #125