feat(wm): add opt to keep focused column centered on scrolling layout

This commit adds a new option under layout_options.scrolling -
"center_focused_column", which defaults to false. When

set to true, and when the number of scrolling columns is an odd number
>=3, komorebi will, if there are enough windows being managed on the
workspace, and if the focused window is not too close to either the
beginning or the end of the workspace ring, keep the focused window in a
centered position in the layout

schema.json

@@ -1814,6 +1814,10 @@
                         "columns"
                       ],
                       "properties": {
+                        "center_focused_column": {
+                          "description": "With an odd number of visible columns, keep the focused window column centered",
+                          "type": "boolean"
+                        },
                         "columns": {
                           "description": "Desired number of visible columns (default: 3)",
                           "type": "integer",