[SQL] `az sql mi endpoint-certificate`: Add atomic commands

[ostojicb]

Related command az sql mi

Description

azcli counterpart of https://github.com/Azure/azure-powershell/pull/17703

Testing Guide

History Notes

[Component Name 1] BREAKING CHANGE: az command a: Make some customer-facing breaking change [Component Name 2] az command b: Add some customer-facing feature

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[yonzhan]

SQL