feat: add admin screens, permissions and navigation

Seven admin controllers in a "Studia BM" navigation group, guarded by
jz.bm.access_courses, jz.bm.access_schedule and jz.bm.access_materials,
with Polish and English labels. Date and time fields are checked by the
models before a save and answered as 422 on the field.

controllers/materials/config_form.yaml

@@ -0,0 +1,12 @@
+name: jz.bm::lang.materials.form
+form: ~/plugins/jz/bm/models/materials/fields.yaml
+modelClass: Material
+defaultRedirect: jz/bm/materials
+
+create:
+    redirect: jz/bm/materials/update/:id
+    redirectClose: jz/bm/materials
+
+update:
+    redirect: jz/bm/materials
+    redirectClose: jz/bm/materials

controllers/materials/config_list.yaml

@@ -0,0 +1,15 @@
+list: ~/plugins/jz/bm/models/materials/columns.yaml
+modelClass: Material
+title: jz.bm::lang.materials.title
+recordUrl: jz/bm/materials/update/:id
+noRecordsMessage: backend::lang.list.no_records
+recordsPerPage: 50
+perPageOptions: [20, 50, 100]
+showCheckboxes: true
+defaultSort:
+    column: created_at
+    direction: desc
+toolbar:
+    buttons: [create, delete]
+    search:
+        prompt: backend::lang.list.search_prompt