multimedia/m{player|encoder}: switch to graphics/openjpeg (+)

Mplayer engine indeed require openjpeg >= 2.1.0.
Depend on openjpeg15 is irrelevant, player even connot link with it.

MFH: 2022Q1
Approved by: portmgr (fix build blanket)
Sponsored by: Netzkommune GmbH