Reorganize environment.yml files

[jdhughes-usgs]

Since pyproject.toml has been setup to install required, lint, test, and optional dependencies a single development environment.yml should be created.

• [X] The revised environment.yml should have all of the dependencies inpyproject.toml
• [X] The revised environment.yml should be in the root repo directory.
• [ ] All of the other environment.yml files should be eliminated.
• [X] README.md should be updated to reflect changes.
• [X] Should evaluate if *.txt equivalents of environment.yml are needed. Delete if not needed.

[jmccreight]

There is still a joint mf6/flopy development env file to be reconciled: pwsmf6nb.yml in the root dir.

[jmccreight]

The pwsmf6nb.yml seems to no longer relevant, it was eliminated.

We do, however, no hwave environment.yaml environment_w_jupyter.yaml where the former does not include jupyter dependencies because this causes problem with installation when using WholeTale.