mtmd : add video input support (#24269)

• wip

• ok: lazy bitmap API

• remember to free lazy text

• wip

• add mtmd_helper_video

• support video input on server (base64 input)

• add MTMD_VIDEO config

• add timestamp

• update CLI

• cli: allow auto-completion for video

• add --video arg

• fix build

• update docs

• rename as suggested