Addition of prop types to TableExpandHeader lead to invalid prop warnings

[joshblack]

Over in: f3422c4 we introduced prop types for TableExpandHeader, however, this component is typically used without any props in our examples and usage guidance. As a result, individuals who have updated to the latest are seeing prop warnings for now required props that aren't necessarily required.

We should double-check our prop types for this component and see if we need to add conditional validation for these required props for the default use-case of <TableExpandHeader />