Switch from `qiskit.algorithms` to `qiskit_algorithms`

[mrossinek]

Summary

This replaces all usage of the deprecated qiskit.algorithms module with the new qiskit_algorithms one provided by the corresponding community project.

Closes #1250

Details and comments

Right now, this will still fail CI because I need to handle cases where isinstance checks are going to fail. I am using CI to tell me where this occurs. What remains to be done is:

• [x] fix the isinstance check cases
• [x] update all unittests to use qiskit_algorithms
• [x] update all docs - tutorials, howtos, getting started sample etc

[mrossinek]

I don't understand why mypy is failing here. Will need to dig into this tomorrow...

[coveralls]

Pull Request Test Coverage Report for Build 6186528393

• 22 of 22 (100.0%) changed or added relevant lines in 15 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.008%) to 86.76%

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Totals
Change from base Build 6161449500:	0.008%
Covered Lines:	8709
Relevant Lines:	10038

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💛 - Coveralls

[mrossinek]

CI of commit c07c3e00c868be91c1e4a19036af7791f15aa36c has successfully passed. This indicates that, even though the qiskit_nature module has been fully switched over to use qiskit_algorithms, the deprecated module qiskit.algorithms is still supported (since the tests have not been switched over yet).

In the next commits, I will update the docs and tests to use the new qiskit_algorithms. We will not test the working support of qiskit.algorithms going forward.

[mrossinek]

I have addressed the previous comment and also updated all occurrences of algorithm_globals. See df0137c5c982682e0469f0840af61093ac3826b6 for more details on the latter.

[woodsp-ibm]

One other thing - this also uses qiskit.utils validation eg like this in places from qiskit.utils.validation import validate_min this should get changed to from qiskit_algorithms.utils.validation import validate_min as the validation.py file, originally done in Aqua for algorithms will be deprecated/removed from Qiskit. (Just two uses that I saw)