🔇 fix: Hide Button Icons from Screen Readers (#10776)

If you've got a screen reader that is reading out the whole page,
each icon button (i.e., `<button><SVG></button>`) will have both
the button's aria-label read out as well as the title from the
SVG (which is usually just "image").

Since we are pretty good about setting aria-labels, we should instead
use `aria-hidden="true"` on these images, since they are not useful
to be read out.

I don't consider this a comprehensive review of all icons in the app,
but I knocked out all the low hanging fruit in this commit.

client/src/components/SidePanel/Agents/AgentPanel.tsx

@@ -512,7 +512,7 @@ export default function AgentPanel() {
                   localize('com_ui_agent')
                 }
               >
-                <Plus className="mr-1 h-4 w-4" />
+                <Plus className="mr-1 h-4 w-4" aria-hidden="true" />
                 {localize('com_ui_create') +
                   ' ' +
                   localize('com_ui_new') +