[compleseus] Devide search functions into 2 intial input variants

[kenkangxgwe]

Each consult search function now comes with two variants regarding initial input. They all initialize the input with region content if a region is active, but differ on whether an empty string or thing-at-point if a region is not active.

This change tries to mimic the search behaviors configured in helm layers. Thus the default empty variants are bound to lowercase keys, and the default thing-at-point variants are bound to uppercase keys.

[kassick]

Ha! I ended up doing the same in in my config