title: Port QRegExp::exactMatch() in Qt6
body: <p>I'm porting a Qt5 application to Qt6. I want to move away from Qt5CoreCompat module of Qt6 as soon as possible. My problem is with <code>QRegExp</code> class which should be replaced with <code>QRegularExpression</code> class. Most patches are relatively trivial but how can I port <a href="https://doc.qt.io/qt-5/qregexp.html#exactMatch" rel="nofollow noreferrer"><code>QRegExp::exactMatch()</code></a> in Qt6. Here is some code from the application:</p>
  <pre class="lang-cpp prettyprint-override"><code>QRegExp version(QLatin1String(&quot;(.+)_v(\\d+)&quot;));
  if (version.exactMatch(completeBaseName/*QString*/))
  {
          // some code
  }
  </code></pre>
  <p>I don't see a way to do this in <code>QRegularExpressionMatch</code> class. I guess solution might be something like this:</p>
  <pre class="lang-cpp prettyprint-override"><code>QRegularExpression version(QLatin1String(&quot;(.+)_v(\\d+)&quot;));
  QRegularExpressionMatch match = version.match(completeBaseName);
  if (match.hasMatch())
  {
          // Find exact match or not
  }
  </code></pre>
  <p>I want to have the same behavior as before.</p>