dev/core#4960 Make Case menu link in relationship tab conditional

[ejegg]

Only add the link when CiviCase is enabled

Fixes: https://lab.civicrm.org/dev/core/-/issues/4960

Overview

Fix a regression stopping the Relationship tab from loading active relationships when CiviCase not active

Before

On 5.70, deactivate CiviCase and load the relationship tab of a contact with active relationships. The active relationships do not load and an ajax call returns with http status 500

After

Relationship tab loads normally whether CiviCase is active or not

[civibot]

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[colemanw]

Thanks @ejegg can you rebase this for the 5.70 branch?

[ejegg]

OK, I think that's rebased it @colemanw

[colemanw]

Looks perfect! Thanks @ejegg

[ejegg]

Seems like an unrelated test fail: api_v3_ContributionTest.testSendConfirmationPayLater

[colemanw]

Our test infra is having a bad day.

[colemanw]

@civicrm-builder retest this please

[colemanw]

retest this please