Implemented the section's edit function

I18N Commander/Processor/SectionProcessor.cs

@@ -108,4 +108,31 @@ public static class SectionProcessor
         
         return await db.Sections.CountAsync(n => n.Parent == section);
     }
+
+    public static async Task<Section> RenameSection(DataContext db, string selectedNodeKey, string alteredName)
+    {
+        // Read the section from the database:
+        var section = await db.Sections.FirstOrDefaultAsync(n => n.DataKey == selectedNodeKey);
+        if (section is null)
+            throw new ArgumentException($"The section with key {selectedNodeKey} does not exist in the database.");
+        
+        // Determine the new key:
+        var newKey = string.Join('_', alteredName.Split(' ', StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries)).ToUpperInvariant();
+        
+        // Check, if this key already exists:
+        if (await db.Sections.AnyAsync(n => n.DataKey == newKey))
+        {
+            var rng = new Random();
+            while (await db.Sections.AnyAsync(n => n.DataKey == newKey))
+            {
+                // Add a random number to the end of the key:
+                newKey += $"_{rng.Next(1, 10_000)}";
+            }
+        }
+        
+        section.Name = alteredName;
+        section.DataKey = newKey;
+        await db.SaveChangesAsync();
+        return section;
+    }
 }