[FIX] web_editor: inserting icon it replaces another

Before this commit:

-On inserting icon in note, it replaces another icon.It occurs because
`isEmpty(block)` returns true, when block element was font-awesome, which
causes the code in `insert` method to remove current node, resulting in removal
of previous icon.

After this commit:

-Now icon is added without replacing the another icon.

task-3482264

closes #152929

X-original-commit: 9a94877
Signed-off-by: Antoine Guenet (age) <age@odoo.com>

addons/web_editor/static/src/js/editor/odoo-editor/src/utils/utils.js

@@ -1817,7 +1817,7 @@ export function isEmptyBlock(blockEl) {
     if (!blockEl || blockEl.nodeType !== Node.ELEMENT_NODE) {
         return false;
     }
-    if (visibleCharRegex.test(blockEl.textContent)) {
+    if (isFontAwesome(blockEl) || visibleCharRegex.test(blockEl.textContent)) {
         return false;
     }
     if (blockEl.querySelectorAll('br').length >= 2) {