Add deny list support and workaround for RPM CoW
    
    A couple of issues were encountered when using RPM CoW for some
    packages. This change adds a deny list mechanism to disable RPM CoW for
    specific packages.
    
    Some packages have errors in the signature header. These errors do not
    prevent installation of the package but cause issues in rpm2extents
    conversion. This commit implements the same fix as in
    unloadImmutableRegion.