Preview message URLs only once

If a message lists the same URL twice, the URL would be previewed twice.
This includes Markdown code explicitly using the URL as the link text.
e.g.
        ```
        [http://example.com/](http://example.com/)
        ```

Strip out duplicate URLs when parsing them out,so we only show
a single preview.

Co-authored-by: Evgeniy Kulesh <evgeniyk@seekingalpha.com>

app/lib/server/functions/insertMessage.js

@@ -119,7 +119,7 @@ export const insertMessage = function(user, message, rid, upsert = false) {
 
 		const urls = message.html.match(/([A-Za-z]{3,9}):\/\/([-;:&=\+\$,\w]+@{1})?([-A-Za-z0-9\.]+)+:?(\d+)?((\/[-\+=!:~%\/\.@\,\(\)\w]*)?\??([-\+=&!:;%@\/\.\,\w]+)?(?:#([^\s\)]+))?)?/g);
 		if (urls) {
-			message.urls = urls.map((url) => ({ url }));
+			message.urls = [...new Set(urls)].map((url) => ({ url }));
 		}
 
 		message = Markdown.mountTokensBack(message, false);

app/lib/server/functions/parseUrlsInMessage.js

@@ -10,7 +10,7 @@ export const parseUrlsInMessage = (message) => {
 
 	const urls = message.html.match(/([A-Za-z]{3,9}):\/\/([-;:&=\+\$,\w]+@{1})?([-A-Za-z0-9\.]+)+:?(\d+)?((\/[-\+=!:~%\/\.@\,\w]*)?\??([-\+=&!:;%@\/\.\,\w]+)?(?:#([^\s\)]+))?)?/g) || [];
 	if (urls) {
-		message.urls = urls.map((url) => ({ url }));
+		message.urls = [...new Set(urls)].map((url) => ({ url }));
 	}
 
 	message = Markdown.mountTokensBack(message, false);