fixed checkbox column

## Expected Behavior

When resizable columns are used, it's often useful to be able to exclude a column from being resizable, for example when the leftmost column is just a checkbox.
## Current Behavior

Currently, there is no built in way to exclude a column from being resizable.

As an attempt I added a width to the first column, but it gets overwritten when the browser is resized. When resizable is false the width works ok.

## Steps to Reproduce (for bugs)

It's a feature request not a bug.

Start by locating the resizable-column implementation and the options that control column resizing. Check how the first checkbox column is represented and how widths are recalculated on browser resize. Done means users can mark a column as non-resizable while other columns continue resizing, with coverage for that behavior.

Written by the indexing model from the issue text.