Add oui-overflow* CSS utilities

[BSFishy]

Is your feature request related to a problem? Please describe.

Currently, there is no way to apply the overflow CSS property in OUI. This property is extremely useful in determining what to do when the contents of a container overflow out of the container.

Describe the solution you'd like

The simplest and cleanest way would be to add a few new CSS utilities. These would allow setting overflow to a few settings: visible, hidden, scroll, and auto. Additionally, individual overflow-x and overflow-y utilities should be made available too.

.oui-overflowVisible { overflow: visible !important; }
.oui-overflowHidden { overflow: hidden !important; }
.oui-overflowScroll { overflow: scroll !important; }
.oui-overflowAuto { overflow: auto !important; }

.oui-overflowXVisible { overflow-x: visible !important; }
.oui-overflowXHidden { overflow-x: hidden !important; }
.oui-overflowXScroll { overflow-x: scroll !important; }
.oui-overflowXAuto { overflowx: auto !important; }

.oui-overflowYVisible { overflow-y: visible !important; }
.oui-overflowYHidden { overflow-y: hidden !important; }
.oui-overflowYScroll { overflow-y: scroll !important; }
.oui-overflowYAuto { overflow-y: auto !important; }

Describe alternatives you've considered

I also considered creating a utility component to achieve this. It might look something like this:

return (
  <OuiOverflow direction="both" value="auto">
    {/* Contents with overflow: auto set */}
  </OuiOverflow>
);

However, given the simplicity of the need, I think having an entire component for this would be extremely overkill and not worth the maintaining effort.

Additional context

This gap was identified as part of an OUI compliance audit: opensearch-project/OpenSearch-Dashboards#4122

[joshuarrrr]

The problem with a utility class is that it offloads the usage burden to developers and implementers. I think many of these cases where we want particular overflow behavior are themselves a bit more generalizable (such as resizable panels with min-sized content). Before we decide one way or another, I think we want to bring visual examples from all the audits of plugins which are using specific overflow behaviors.