Deprecate the repository and pip package

[farhan]

Ticket: openedx/XBlock#675

PR implementation details:
Add a deprecation warning in:

1. a readme file
2. all the modules to show a warning while importing deprecated modules from a deprecated package

For readme preview:
https://github.com/openedx/xblock-utils/blob/farhan/deprecate-repo/README.rst

Implementation inspiration:
https://github.com/openedx/edx-platform/blob/master/docs/decisions/0007-sys-path-modification-removal.rst
https://github.com/openedx/edx-platform/tree/open-release/koa.1/import_shims

How deprecated warning will appear in the console:

[salman2013]

@farhan Could you please look at the test failure.

[farhan]

@farhan Could you please look at the test failure.

@salman2013 fixed

[feanil]

@farhan we should also remove the old code from these files and replace it with wildcard imports of the new locations. That way we are not maintaining two copies of the code that can get out of sync and the shell of xblock-utils continues to work as we make changes in the upstream repo.

[feanil]

Looks like this is on the right track and should be good to land once the tests have been fixed and you've tested locally that an XBlock that still uses xblock-utils runs and produces the expected warnings.

[farhan]

Looks like this is on the right track and should be good to land once the tests have been fixed and you've tested locally that an XBlock that still uses xblock-utils runs and produces the expected warnings.

@feanil test cases fixed
I have done the testing on the DoneXblock
I installed the xblock-utils zip 4.0.0 with the command pip install xblock-utils-4.0.0.zip
and verify the working of the Done Xblock

Terminal Screen Shots

🤔
Shouldn't we remove the test case in this repository as these test cases are running on the xblock.utils package while we are already running the test cases within xblock repo as well?

[feanil]

@farhan yea, once we're happy with this, we can drop all the tests but it's useful to have them to make sure we did all the import redirecting correctly. It makes sense that those tests would need to be updated because of how the ResourceLoader class is being imported now within the XBlock library but it was good to verify we didn't break any non-test functionality of calling the imports the old way in the tests.

[feanil]

Changes look great, I left a minor suggestion in the language of the import warning that you can take or leave. Feel free to merge and make a final release of this repo.