feat(float): allow enabling mouse for non-focusable window (#30844)

Problem:  Cannot allow mouse interaction for non-focusable float window.
Solution: Add a "mouse" field to float window config.

runtime/lua/vim/_meta/api_keysets.lua

@@ -295,6 +295,7 @@ error('Cannot require a meta file')
 --- @field bufpos? any[]
 --- @field external? boolean
 --- @field focusable? boolean
+--- @field mouse? boolean
 --- @field vertical? boolean
 --- @field zindex? integer
 --- @field border? any