Move away from `console_script` entrypoints

[jhkennedy]

Inthe past, we've created command line (console-script) entrypoints for hyp3 plugins, making a "hyp3" entry point(s), and a "science" entry point which has more available options. For example, in hyp3-gamma:

• the main "HyP3" entrypoint: https://github.com/ASFHyP3/hyp3-gamma/blob/develop/setup.py#L61 which can also be called on the command line like python -m hyp3_gamma
• The HyP3 RTC entry point: https://github.com/ASFHyP3/hyp3-gamma/blob/develop/setup.py#L62 which can also be called on the command line like python -m hyp3_gamma ++process RTC
• the "Science" HyP3 RTC entry point: https://github.com/ASFHyP3/hyp3-gamma/blob/develop/setup.py#L63 which is just a general RTC workflow script not tied to HyP3

For this cookiecutter:

1. we don't need to register any HyP3 console script entry points as the hyp3 entry points are already accessible on the command line via python -m
2. we don't need to register extra "science" entry points as this is a cookie cutter intended to help you develop a hyp3-plugin, and not every plugin will need a CLI version of the "science" code (e.g., "scientists" may prefer jupyter notebooks and not use the command line at all)

Accordingly, I believe we can:

• [x] drop these lines in the pyproject.toml: https://github.com/ASFHyP3/hyp3-cookiecutter/blob/update_staging/%7B%7Bcookiecutter.project_name%7D%7D/pyproject.toml#L29-L32
• [x] drop the process_name test: https://github.com/ASFHyP3/hyp3-cookiecutter/blob/update_staging/%7B%7Bcookiecutter.project_name%7D%7D/tests/test_entrypoints.py#L6-L8
• [x] update the package_name test to invoke the package __main__ entry point like python -m {{cookiecutter.package_name}} -h

[jtherrmann]

Relates to https://github.com/ASFHyP3/hyp3-cookiecutter/issues/9