Make public getDictionaryDefinition (#20759)
Fixes #20675
Summary of the issue:
speechDictHandler.dictionaries is deprecated without public replacement. Therefore, there's not any public component in the API to manipulate existing dictionaries for add-ons.
Description of user facing changes:
Description of developer facing changes:
speechDictHandler.definitions._getDictionaryDefinition can be used to get speech dictionary definitions, which may be used to manipulate speech dictionaries.
Description of development approach:
speechDictHandler.definitions._getDictionaryDefinition is marked as public, and calls to the private function have been replaced with the public one.
