Add `modify_table_styling()` checks?

[ddsjoberg]

Generally, this function does not perform checks on user input. It's expected that that function is primarily used by devs to create new tabling functions, and the inputs should be verified prior to calling the function OR the dev should know what is accepted/not accepted.

Also, nearly every feature that is modifiable here has a sister function that has a nicer API, and those functions have checks....

By not adding checks here, the internal functions could be mildly quicker to run. But is that worth it?

If we do add them, we should move the checks from the sister functions, and let them be handled by this function? Although, the messaging would be difficult to get exactly right....