* Migrate old alerting templates to use $labels
* Fix imports
* Add test coverage and separate rewriting to Go templates
* Fix lint
* Check for additional closing braces
* Add logging of invalid message templates
* Fix tests
* Small fixes
* Update comments
* Panic on empty token
* Use logtest.Fake
* Fix lint
* Allow for spaces in variable names by not tokenizing spaces
* Add template function to deduplicate Labels in a Value map
* Fix behavior of mapLookupString
* Reference deduplicated labels in migrated message template
* Fix behavior of deduplicateLabelsFunc
* Don't create variable for parent logger
* Add more tests for deduplicateLabelsFunc
* Remove unused function
* Apply suggestions from code review
Co-authored by: Yuri Tseretyan <yuriy.tseretyan@grafana.com>
* Give label val merge function better name
* Extract template migration and escape literal tokens
* Consolidate + simplify template migration
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Co-authored-by: William Wernert <william.wernert@grafana.com>