Move AlertManagementAlertResolver into module

What does this MR do?

Moves the AlertManagementAlertResolver into the AlertManagement module. We end up with AlertManagement::AlertResolver, which matches the other types.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Closes #217909 (closed)