fix(to_cpp1): support initializing assignment from expression list in `operator=`

[JohelEGP]

Resolves #679.

Testing summary:

100% tests passed, 0 tests failed out of 818

Total Test time (real) =  48.87 sec

Acknowledgements:

• Tested thanks to https://github.com/modern-cmake/cppfront.
• Commit messages follow Conventional Commits 1.0.0.
• Comments and commit messages follow Semantic Line Breaks.

[hsutter]

Hi! Sorry it took me so long to get to this one... but this is really tactical and looks like it might still be current, modulo the conflict.

Is this up to date (after resolving the merge conflict), and would you like me to review it?

[JohelEGP]

Yes, and yes.