Add Migration Guide for qiskit.algorithms (Qiskit/qiskit#9557)

* Add draft

* Remove qiskit

* Apply review

* Add algos guide

* Add skeleton

* Add content

* Fix sampling VQE example

* Apply suggestions from Steve's code review

Co-authored-by: Steve Wood <40241007+woodsp-ibm@users.noreply.github.com>

* Apply review, update code examples up to Eigensolvers

* Add doctest to sphinx config

* Add tests up to eigensolvers

* Review code examples from Eigensolvers

* Update heading style

* Apply suggestions from Declan's code review

Co-authored-by: Declan Millar <declan.millar@ibm.com>

* Apply suggestions from Steve's code review

Co-authored-by: Steve Wood <40241007+woodsp-ibm@users.noreply.github.com>

* Apply review

* Final changes, fix docs

* Apply Julien's comments

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Co-authored-by: Steve Wood <40241007+woodsp-ibm@users.noreply.github.com>
Co-authored-by: Declan Millar <declan.millar@ibm.com>