Added PowerPoint templates to the Slide Assistant (#1055)

Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/MindWork AI Studio/Tools/PowerPoint/PlaceholderRole.cs

@@ -0,0 +1,37 @@
+namespace AIStudio.Tools.PowerPoint;
+
+/// <summary>
+/// What a placeholder of a slide layout is for, as far as filling it is concerned.
+/// </summary>
+/// <remarks>
+/// Templates rarely say what a layout is for: most of them leave the layout type at "custom". So the
+/// role is read from the placeholder itself, its type and its size, and a text placeholder too small
+/// to hold more than a line becomes a label rather than a text.
+/// </remarks>
+internal enum PlaceholderRole
+{
+    /// <summary>
+    /// A placeholder we cannot fill, e.g., a chart or a media placeholder.
+    /// </summary>
+    UNSUPPORTED = 0,
+
+    TITLE,
+    SUBTITLE,
+
+    /// <summary>
+    /// A text area large enough for paragraphs or bullet points.
+    /// </summary>
+    TEXT,
+
+    /// <summary>
+    /// A small text, e.g., a heading above a text area, the source of a picture, or a chapter number.
+    /// </summary>
+    LABEL,
+
+    PICTURE,
+    TABLE,
+
+    FOOTER,
+    SLIDE_NUMBER,
+    DATE,
+}