SSA-6324: All tests pass when run locally. In Docker container, tests that exercise the CLI all fail, unable to find the "datafetcher" entry_point.

SSA-6324: tests pass when run locally; some fail in Docker container. Committing what I've got so as not to lose it after tearing my hair out for a day and a half.

SSA-6324: placate Pylint somewhat; this time -really- get rid of the properties file after the Docker image is built; look what Pathlib can do!

SSA-6324: pytest on datafetcher_test.py executes in a Docker container. capo properties file is copied to the docker build directory, then deleted.

Tests all succeed when executed in IJ.

SSA-6325: a few import and path tweaks were necessary to get all the tests to run from the command line

master: reorganized datafetcher "SDM-only" functionality removed. All tests pass, including those that launch DF from a process to simulate command-line execution. TODO: actual command line, as below, should work but doesn't yet:

datafetcher --profile local --output-dir ~/Downloads --product-locator uid://evla/execblock/93e1c0cd-76de-4e65-a3f2-d5fe55f386d8 --verbose

Pylint also finds some errors, the consequence of fixing which puts red ink in the IJ editor and causes the above-mentioned command-line tests to fail.