feat: Organisations admin screen with the avatar and the members manager

- controller golem15.user.organisations behind golem15.users.access_users
- list and form (name, slug preset from the name, description, avatar)
- members relation manager: link sets and unlink clears users.organisation_id
- deleting an organisation releases its members first
- Organisation gains Fillable, Rules, MorphName, AttachRelations, BeforeValidate
  and the Members relation; models.Slugify
- navigation side item organisations
- TestAdminOrganisations, TestAdminOrganisationMembers, TestSlugify

controllers/organisations/config_form.yaml

@@ -0,0 +1,18 @@
+name: golem15.user::lang.organisation.label
+form: ~/plugins/golem15/user/models/organisation/fields.yaml
+modelClass: Golem15\User\Models\Organisation
+defaultRedirect: golem15/user/organisations
+
+create:
+    redirect: golem15/user/organisations/update/:id
+    redirectClose: golem15/user/organisations
+
+update:
+    redirect: golem15/user/organisations
+    redirectClose: golem15/user/organisations
+
+messages:
+    create: golem15.user::lang.organisation.new
+    update: backend::lang.messages.form.update
+    saved: backend::lang.messages.form.saved
+    deleted: backend::lang.messages.form.deleted

controllers/organisations/config_list.yaml

@@ -0,0 +1,15 @@
+list: ~/plugins/golem15/user/models/organisation/columns.yaml
+modelClass: Golem15\User\Models\Organisation
+title: golem15.user::lang.organisation.label_plural
+recordUrl: golem15/user/organisations/update/:id
+noRecordsMessage: backend::lang.list.no_records
+recordsPerPage: 20
+
+toolbar:
+    buttons: [create]
+    search:
+        prompt: backend::lang.list.search_prompt
+
+messages:
+    create: golem15.user::lang.organisation.new
+    empty: golem15.user::lang.organisation.list_empty

controllers/organisations/config_relation.yaml

@@ -0,0 +1,24 @@
+members:
+    label: golem15.user::lang.organisation.members
+    messages:
+        link: golem15.user::lang.organisation.add_member
+        unlinkSelected: golem15.user::lang.organisation.remove_members
+        unlinkConfirm: golem15.user::lang.organisation.remove_members_confirm
+        empty: golem15.user::lang.organisation.members_empty
+    view:
+        list:
+            columns:
+                name:
+                    label: golem15.user::lang.user.name
+                email:
+                    label: golem15.user::lang.user.email
+        toolbarButtons: link|unlink
+        showSearch: true
+    manage:
+        list:
+            columns:
+                name:
+                    label: golem15.user::lang.user.name
+                email:
+                    label: golem15.user::lang.user.email
+        showSearch: true