feat(chatfom): make magnet links clickable

Add one more rergular expression that should match magnet links.
Unfortunately, magnet links may contain a lot of spaces, so
the message after the link may also be treated as a part of link.

src/chatlog/textformatter.cpp

@@ -90,6 +90,7 @@ static const QVector<QRegularExpression> URI_WORD_PATTERNS = {
     QRegularExpression(QStringLiteral(R"((?<=^|\s)\S*(tox:[a-zA-Z\d]{76}))")),
     QRegularExpression(QStringLiteral(R"((?<=^|\s)\S*(mailto:\S+@\S+\.\S+))")),
     QRegularExpression(QStringLiteral(R"((?<=^|\s)\S*(tox:\S+@\S+))")),
+    QRegularExpression(QStringLiteral(R"((?<=^|\s)\S*(magnet:[?]((xt(.\d)?=urn:)|(mt=)|(kt=)|(tr=)|(dn=)|(xl=)|(xs=)|(as=)|(x.))[\S| ]+))")),
 };