[BUG] unhandled dockerize errors

[AlbertDeFusco]

There is at least one case where s2i build fails and dockerize doesn't catch it appropriately. For example if the image name has uppercase characters. After the error message is printed s2i still attempts to run and the whole process exists with 0.

The dockerize command should at least check for incorrect tag name and stop before getting too far.

anaconda-project dockerize --tag HelloWorld
Archiving project to temporary directory.
  added helloworld/.github/workflows
  added helloworld/.gitignore
  added helloworld/.projectignore
  added helloworld/README.md
  added helloworld/anaconda-project.yml
  added helloworld/hello.py
Warning: env specs are not locked, which means they may not work consistently for others or when deployed.
  Consider using the 'anaconda-project lock' command to lock the project.
Extract : 100%|██████████████████████████████████████████████████████████████████████████████| 6/6 [00:00<00:00, 3070.88it/s]

Starting image build. This may take several minutes.
*** HelloWorld image build starting.
s2i build --copy /var/folders/lk/s__7f9fx15x_zrw6q5xkmm500000gp/T/tmpqmerejhv/project conda/s2i-anaconda-project-ubi8:latest HelloWorld -e CMD=default
ERROR: Invalid value specified for "tag": repository name must be lowercase