Fix: Ensure QubitOperator is simplified before sparse conversion

[Aniketsy]

#880
This PR fixes an issue where get_sparse_operator fails when given a non-simplified QubitOperator

Please let me know if my approach or fix needs any improvements . I’m open to feedback and happy to make changes based on suggestions.
Thankyou !

[mhucka]

Thanks for this contribution. This is currently failing CI tests because the function simplify() does not seem to exist on the object. Could you please investigate?

Also, I highly recommend running tests locally before submitting a PR, to catch problems like this.

[Aniketsy]

Sure, Thanks! I will look into it .

[mhucka]

@Aniketsy Thanks for this contribution. I took the liberty of merging the latest changes from the main branch and pushing a small change to your fork, in an attempt to resolve some remaining errors and warnings. However, it turns out that the warnings about simplification now show up all over the place in the tests. This is surely an indication that the change to get_sparse_operator() is not the right way to solve the underlying problem. Unfortunately, I also lack the domain expertise to figure out the correct solution.

[Aniketsy]

@mhucka thanks for pushing the changes, and I apologize for keeping this PR stale for log time, as i was envolved in other things but I will take a look in this again and i'll try to fix this! :)