fix: a popup reload no longer logs the requests it cancels on most screens (closes #475)

The transaction lists and ENS name lookups on the address and token
screens, the address scan after a wallet is created, the endpoint checks
in Settings, the wait screen's receipt check, the Send screen's Max fee
estimate and the token lookup on both add-token screens now check the
signal the popup aborts on pagehide before reporting a failed request.
scanForAddresses(), resolveEnsNames() and lookupTokenInfo() take the
signal.

End-to-end tests reload the popup on the address screen and during the
address scan with their requests held. Jest tests show each of these
reports a real failure and stays silent once the popup has closed. The
transaction detail and confirmation screens are left out: they discard
the popup context that carries the signal.

Model: opus-5-5

src/popup/views/settings.js

@@ -273,6 +273,9 @@ function init(ctx) {
                 return;
             }
         } catch {
+            // Cancelled by the popup closing, not failed: see pageClosed in
+            // src/popup/index.js.
+            if (ctx.pageClosed.aborted) return;
             // Not the error's message: fetch puts the whole URL, password and
             // key included, in the message of the error it throws for a URL
             // with a user name and password or one it cannot parse.
@@ -299,6 +302,7 @@ function init(ctx) {
                 return;
             }
         } catch {
+            if (ctx.pageClosed.aborted) return;
             // Not the error's message, as for the RPC check above.
             log.errorf("Blockscout validation failed:", urlOrigin(url));
             showFlash("Could not reach endpoint.");