Add an example render to test/demo how the json-seq based progress
works. It needs the python `tqdm` package for the actual rendering.
See the output with:
```
$ sudo OSBUILD_TEST_STORE=/var/tmp/osbuild-test-store \
python3 -m osbuild --libdir=. --monitor=JSONSeqMonitor --export image \
--output-dir=/tmp/output-dir ./test/data/manifests/fedora-boot.json | ./tools/osbuild-json-seq-progress-example-renderer
```
