Add first pre/post upgrade skeleton for Model Registry (#371)

* feat: add first pre/post upgrade skeleton

Signed-off-by: lugi0 <lgiorgi@redhat.com>

* fix: remove unused code and comments

Signed-off-by: lugi0 <lgiorgi@redhat.com>

* fix: remove unused code for tox

Signed-off-by: lugi0 <lgiorgi@redhat.com>

* fix: address review comments

Signed-off-by: lugi0 <lgiorgi@redhat.com>

* feat: add 2.22/oauth checks in post-upgrade

Signed-off-by: lugi0 <lgiorgi@redhat.com>

* fix: address review comments and refactor

Signed-off-by: lugi0 <lgiorgi@redhat.com>

* fix: remove commented out code

Signed-off-by: lugi0 <lgiorgi@redhat.com>

* fix: add missing parameter

Signed-off-by: lugi0 <lgiorgi@redhat.com>

* Update conftest.py

* Add @pytest.mark.post_upgrade to all post upgrade tests

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* fix: small typo in mr instance fixture

Signed-off-by: lugi0 <lgiorgi@redhat.com>

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Signed-off-by: lugi0 <lgiorgi@redhat.com>
Co-authored-by: Debarati Basu-Nag <dbasunag@redhat.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: 3 people