Add PDF printing functionality to editor components

Enabled PDF printing in `SenderPdfImageEditor` and `SenderPdfImageEditorToolbar`. Added `CanPrintPdf` property to determine print availability and a new `OnPrintPdfAsync` method for handling print logic via JavaScript interop. Updated the toolbar with a "Print" button that triggers the print functionality.

Implemented the `printDataUrlPdf` function in `envelope-editor.js` to handle printing from a data URL. This function creates an iframe, loads the PDF, and invokes the browser's print functionality with proper cleanup of resources.

EnvelopeGenerator.Server/EnvelopeGenerator.Server/wwwroot/js/envelope-editor.js

@@ -243,5 +243,82 @@ window.envelopeEditor = {
         host.appendChild(link);
         link.click();
         host.removeChild(link);
+    },
+
+    printDataUrlPdf: async function (dataUrl, mimeType) {
+        if (!dataUrl || typeof dataUrl !== 'string') {
+            return;
+        }
+
+        let objectUrl = null;
+        let printSrc = dataUrl;
+
+        if (dataUrl.startsWith('data:')) {
+            try {
+                const response = await fetch(dataUrl);
+                const blob = await response.blob();
+                objectUrl = URL.createObjectURL(blob);
+                printSrc = objectUrl;
+            } catch {
+                printSrc = dataUrl;
+            }
+        }
+
+        const frame = document.createElement('iframe');
+        frame.style.position = 'fixed';
+        frame.style.right = '0';
+        frame.style.bottom = '0';
+        frame.style.width = '0';
+        frame.style.height = '0';
+        frame.style.border = '0';
+        frame.setAttribute('aria-hidden', 'true');
+
+        const host = document.body || document.documentElement;
+        host.appendChild(frame);
+
+        let cleaned = false;
+        const cleanup = function () {
+            if (cleaned) {
+                return;
+            }
+
+            cleaned = true;
+
+            if (frame.parentNode) {
+                frame.parentNode.removeChild(frame);
+            }
+
+            if (objectUrl) {
+                URL.revokeObjectURL(objectUrl);
+                objectUrl = null;
+            }
+        };
+
+        frame.onload = function () {
+            try {
+                const frameWindow = frame.contentWindow;
+                if (!frameWindow) {
+                    cleanup();
+                    return;
+                }
+
+                frameWindow.addEventListener('afterprint', function () {
+                    window.setTimeout(cleanup, 250);
+                }, { once: true });
+
+                window.addEventListener('focus', function () {
+                    window.setTimeout(cleanup, 1500);
+                }, { once: true });
+
+                frameWindow.focus();
+                frameWindow.print();
+            } catch {
+                cleanup();
+            }
+        };
+
+        frame.src = printSrc;
+
+        window.setTimeout(cleanup, 120000);
     }
 };