a11y: Use VteTerminal private data directly
a11y: Use VteTerminal private data directly

... instead of via the VteTerminal::pvt pointer.

thestinger/vte-ng,saitoha/vte-sixel,thestinger/vte-ng,thestinger/vte-ng,saitoha/vte-sixel,saitoha/vte-sixel