feat: Implement SAM structure mirroring in PostgreSQL for study plans and courses

- Added functionality to save study plans and courses in SAM format to PostgreSQL.
- Updated SQL queries to reflect SAM-native column names and handle conflicts appropriately.
- Introduced new fields in the Asset model for English level and SAM identifiers.
- Enhanced the TestTemplateForm component to manage linked assets and shared materials.
- Created a new AdminSharedMaterialsPage for uploading ZIP files of shared materials.
- Added migrations to create SAM mirror tables and update the assets table with new columns.

shared/common/src/models.rs

@@ -344,6 +344,9 @@ pub struct Asset {
     pub organization_id: Uuid,
     pub uploaded_by: Option<Uuid>,
     pub course_id: Option<Uuid>,
+    pub english_level: Option<String>,
+    pub sam_plan_id: Option<i32>,
+    pub sam_course_id: Option<i32>,
     pub filename: String,
     pub storage_path: String,
     pub mimetype: String,