Add support for copying unknown partitions.

BUG: 447784

src/fs/unknown.cpp

@@ -13,6 +13,7 @@ namespace FS
 {
 
 FileSystem::CommandSupportType unknown::m_Move = FileSystem::cmdSupportCore;
+FileSystem::CommandSupportType unknown::m_Copy = FileSystem::cmdSupportCore;
 
 unknown::unknown(qint64 firstsector, qint64 lastsector, qint64 sectorsused, const QString& label, const QVariantMap& features) :
     FileSystem(firstsector, lastsector, sectorsused, label, features, FileSystem::Type::Unknown)

src/fs/unknown.h

@@ -37,7 +37,12 @@ public:
         return m_Move;
     }
 
+    CommandSupportType supportCopy() const override {
+        return m_Copy;
+    }
+
     static CommandSupportType m_Move;
+    static CommandSupportType m_Copy;
 };
 }