Set Constellation Command (#1565)

Original commits:

* create `SetConstCommand` class and translations

* (partially) functional `setconst` command

* fixed punctuation

* added success message

* implemented `SetConstCommand`

* added translation keys

* update keys

* refactor + automatic reload

* Nitpick (Co-authored-by: AnimeGitB <AnimeGitB@bigblueball.in&gt;)>