accepting window value for cache_window

[krehwell]

my workflow is to open edit by default (just like harpoon)

this PR is to allow user to edit the size of edit buffer window.

for people who work with monorepo, it is normal to have long file path, I want my window to be a lot bigger than the default

[krehwell]

@otavioschwanck any update if are you gonna merge this?