refactor(alertsmanagement): migrate to unified folder structure (Azure#38560)

* Handle SmartDetectorAlertRulesApi

* Handle AlertProcessingRules and PrometheusRuleGroup

* More services

* Finish all the rest

* Fixes

* Add missing example

* Move AlertRules to AlertProcessingRules

* Undelete missing files

* Delete redundant readme file

* APR - round 1

* APR - fix

* Fix ```

* SmartDetectorAlertRules readmes

* PrometheusRuleGroups and SmartGroups

* Fix in PrometheusRuleGroups

* AlertRuleRecommendations

* Issue

* Issues - fix

* MigrateFromSmartDetections

* PreviewAlertRule

* TenantActivityLogAlerts

* AlertsManagement - cleanup

* Fixes after cleanup

* Add suppressions to various LintDiff errors

* More suppressions for LintDiff

* Move to legacy

* Adjust "legacy" folder

* Add missing tags under legacy

* Suppress old private preview version

* Add typespec requirement suppressions

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Co-authored-by: Liad Tal <lital@microsoft.com>

Author: liadtal