Axis Labels: Add the ability to truncate

<!-- Please only use this template for submitting feature requests --> **Why is this needed**: When designing panels with long axis labels (especially horizontal bar charts), the labels get cropped if the panel is not big enough. This already works for vertical bar charts, but not for horizontal ones. Example screenshot of the issue:  **What would you like to be added**: We need an option to define a truncation/ellipsis strategy for axis labels in the most common panel types. Ideally this includes the option to truncate either at the start, in the middle or at the end. **Who is this feature for?** Everyone building dashboards.