Improve sender field in mail notifications

Problem statement: user sees its email address in email notification,
while it is better to have sender field app-personalized, like it did
in Nextcloud: they send notifications from user's email address and
add alias 'Nextcloud' to it.

This patch adds alias 'qBittorrent' to qBittorrent email notifications,
so user sees more user-friendly email notification.

PR #17374.

src/app/application.cpp

@@ -476,7 +476,7 @@ void Application::sendNotificationEmail(const BitTorrent::Torrent *torrent)
     auto *smtp = new Net::Smtp(this);
     smtp->sendMail(pref->getMailNotificationSender(),
                      pref->getMailNotificationEmail(),
-                     tr("[qBittorrent] '%1' has finished downloading").arg(torrent->name()),
+                     tr("Torrent \"%1\" has finished downloading").arg(torrent->name()),
                      content);
 }
 

src/base/net/smtp.cpp

@@ -138,7 +138,7 @@ void Smtp::sendMail(const QString &from, const QString &to, const QString &subje
 {
     const Preferences *const pref = Preferences::instance();
     m_message = "Date: " + getCurrentDateTime().toLatin1() + "\r\n"
-                + encodeMimeHeader(u"From"_qs, from)
+                + encodeMimeHeader(u"From"_qs, u"qBittorrent <%1>"_qs.arg(from))
                 + encodeMimeHeader(u"Subject"_qs, subject)
                 + encodeMimeHeader(u"To"_qs, to)
                 + "MIME-Version: 1.0\r\n"