Move conftest for tests

[jzuhone]

Description

Attempting to run the acisfp_check regression tests from the ska3 flight repository results in an error:

import acisfp_check
acisfp_check.test()

...  many errors like this:

____________________ ERROR at setup of test_DEC0919A_viols _____________________
file /Users/aldcroft/miniconda3/envs/ska3/lib/python3.8/site-packages/acisfp_check/tests/test_acisfp_viols.py, line 7
  def test_DEC0919A_viols(answer_store, test_root):
E       fixture 'answer_store' not found
>       available fixtures: capfd, capfdbinary, caplog, capsys, capsysbinary, doctest_namespace, monkeypatch, pytestconfig, record_property, record_testsuite_property, record_xml_attribute, recwarn, tmp_path, tmp_path_factory, tmpdir, tmpdir_factory
>       use 'pytest --fixtures [testpath]' for help on them.

This PR moves the conftest.py file to the actual package so it gets copied over in the install.

Testing

• Passes unit tests on MacOS, linux, Windows (at least one required)

Fixes issue #30

[taldcroft]

I tried this out on my Mac by doing a --user install in the flight Ska3 environment. I confirmed that the imported package is this version and then verified that acisfp_check.test() runs and passes all tests.

I haven't tried all the others, leaving approval of these to other ACISops folks, but it looks like just moving the file into the package does the trick.