[ticket/12773] Fix language variable name in cli extension enable command

PHPBB3-12773
Merge pull request #2661 from n-aleha/ticket/12773

[ticket/12773] Fix language variable name in cli extension enable command

* n-aleha/ticket/12773:
  [ticket/12773] Fix language variable name in cli extension enable command
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/12773] Fix language variable name in cli extension enable command