Add cleanUpFilter() method for proper resource cleanup in SoftBloomFilter

[capdevon]

I think the SoftBloomFilter should have a cleanUpFilter() method to properly clean up textures and resources used during the downsampling and upsampling passes, which could lead to memory or GPU leaks.

This would bring it in line with other filters in jME and improve resource management.

    @Override
    protected void cleanUpFilter(Renderer r) {
        for (Pass p : downSamplingPasses) {
            p.cleanup(r);
        }
        for (Pass p : upSamplingPasses) {
            p.cleanup(r);
        }
        initialized = false;
    }

[capdevon]

Fixed #2611