Send surroundingText and content hints/purpose to inputmethod

Previously we were either sending out this information to InputMethod of the QApp (i.e kwin itself) which is no longer case since we switched to using the proper wayland protocol instead of the qtvirtualkeyboard inside the kwin.

This fixes the issue with the weston-keyboard at least that in field which accepts digits it shows the keyboard with digit layout. I still have some issues with maliit-keyboard but that might be bug on the maliit-keyboard side.