Fix updating of checkbox when user accepts permissions request (#29)

When the user requests the extension to be given access to the site
and confirms this in the consequent browser dialog, the context menu
item wasn't being immediately changed to checked.

We can fix this by ensuring that the updateItem() function which is
responsible for updating the checkmark is called with the correct URL
for the tab in question, so that it can detect whether the permission
is now granted to the site and update the context menu item
accordingly.

Note that the browser will automatically enable the checkmark simply
by virtue of the context menu item having been clicked.  So if the
user denies access in the dialog (despite previously requesting it to
be given via a user-initiated "gesture", which is the only way the
chrome.permissions API allows access to be given), then
chrome.contextMenus.update() needs to be called to reverse that
enabling of the checkmark.  However by calling `updateItem()` within
the `finally` block with the correct tab URL, we can ensure the
checkmark is always correctly set regardless of what happened.

Fixes #29.

index.ts

@@ -71,9 +71,6 @@ async function togglePermission(tab: chrome.tabs.Tab, toggle: boolean): Promise<
 
 	const userAccepted = await chromeP.permissions.request(permissionData);
 	if (!userAccepted) {
-		chrome.contextMenus.update(contextMenuId, {
-			checked: false,
-		});
 		return;
 	}
 
@@ -117,7 +114,7 @@ async function handleClick(
 
 		throw error;
 	} finally {
-		void updateItem();
+		void updateItem(tab?.id ? await getTabUrl(tab?.id) : '');
 	}
 }