Some things should be typehinted with ConfigurableLanguageManagerInterface not LanguageManagerInterface

Problem/Motivation

Noticed in #2212427-21: Use interface instead of class name for language manager where appropriate. → :
Some things should be typehinted with ConfigurableLanguageManagerInterface not LanguageManagerInterface because they depend on functionality in the ConfigurableLanguageManager that comes with the language module.

Proposed resolution

typehint with ConfigurableLanguageManagerInterface (not LanguageManagerInterface) in ... ?

Remaining tasks

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• Identify which should be ConfigurableLanguageManagerInterface not LanguageManagerInterface
• git instructions for creating patch | Contributor task documentation for creating a patch
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User interface changes

No.

API changes

Yes.