Move visualeditor-languages-tool message from ve to ve-mw

I intially thought it was associated with the language inspector, but
it's not, it's the label for the languages pane in the meta dialog.

Change-Id: I478e3951862a25eee056e3df6cc3c9f9f7d9d935
Merge "Move visualeditor-languages-tool message from ve to ve-mw"