[FEATURE] Support greasyfork for "Search available scripts" feature

[limex]

Current behavior:

• Given the icon in the icon bar is pressed, I can see if there are scripts available for the current website showing "Found x available scripts"
• This search results are via Userscript.Zone.
• Given I press on ""Found x available scripts", the link goes to Userscript.Zone showing the respective scripts.

Desired behavior:

• Add a configuration to get the search results from GreasyFork and jump to GreasyFork.org for the results.

Context:

• GreasyFork adds and hosts more user scripts than Userscript.zone
• Manual search on GreasyFork is possible but very inconvenient, seeing that Greasy Fork hosted scripts are available for the site on the icon would be great.