feat: add ivy-style layout strategy (#771)

* feat: add new layout strategy

* [docgen] Update doc/telescope.txt
skip-checks: true

Co-authored-by: Github Actions <actions@github>

scripts/gendocs.lua

@@ -15,6 +15,7 @@ docs.test = function()
     "./lua/telescope/actions/state.lua",
     "./lua/telescope/actions/set.lua",
     "./lua/telescope/previewers/init.lua",
+    "./lua/telescope/themes.lua",
   }
 
   table.sort(input_files, function(a, b)