Refactor utils.py into a utils module to reduce code complexity and prune out unused utils.

[matteius]

Placeholder for news item for PR Ref: #4990

The issue

The pipenv/utils.py has grown to 2338 lines of code, which makes it unwieldy and disorganized. When trying to consider larger bugs and refactors this is problematic because of the logical complexity of navigating around and understanding what kind of util you are looking at. I would like to do something similar with core.py at some point as well, but this is my first iteration of proposing reorg'ing some of the code.

The fix

Move the existing utils.py code into a utils module organized by functionality type. This is a first pass at it, and I suspect there may be some tweaking to my naming conventions to make everyone happy. The only draw back I see to doing this is loosing some of the git annotations around this code, but ultimately that would happen whenever we get around to organizing the code better and I think good code organization is more important than legacy annotations which would still ultimately be in the git history.

The only modifications to code being moved are the following methods have been dropped due to lack of use:

escape_grouped_arguments + unit tests
parse_python_version + unit tests
add_to_set
sys_version
get_indexes_from_requirement
interrupt_handled_subprocess
rmtree
Also two unused code lines were removed pipenv/core.py because I had already run the test suite showing they were not used after my IDE tipped me off about that.

[matteius]

PR was merged to main.