fix: use more robust method of finding matches for major version

This uses the proper version list to find all MC versions matching the
major number (_don't say anything about SemVer_ 🔫).

Signed-off-by: flow <flowlnlnln@gmail.com>

launcher/meta/VersionList.h

@@ -66,6 +66,7 @@ public:
     QString humanReadable() const;
 
     VersionPtr getVersion(const QString &version);
+    bool hasVersion(QString version) const;
 
     QVector<VersionPtr> versions() const
     {