[Feature] Only show the first implementation

[kianNgyn]

Describe the bug
When use "goto implementation", if there are several implementations, it's only show the first one and have no way to choose the other

[chaozwn]

i think maybe we can use rust-analyzer solution like this. show the mutiple selection in the top.

[chaozwn]

reference link: https://github.com/mrcjkb/rustaceanvim/blob/master/lua/rustaceanvim/hover_actions.lua#L92

[rmagatti]

I suppose what we'll want here is for goto-preview to do the same thing it does when require("goto-preview").goto_preview_references() is called, which is to open a picker with the multiple references, in this case, the multiple implementations to pick from and then open the preview, yes?