Add API for retrieving the rendered names of all columns (including hidden ones)

[DuckyCrayfish]

Currently there does not exist a way to list the rendered column names of all columns, including hidden columns, since getAllColumns() only works on visible columns.

Here's a couple answers to help provide some context:

"Why?"
This would be useful for displaying a dynamically generated list of columns in a column visibility menu.

"You already can, check the examples"
The column toggler in the examples uses column ID, which in my case is not user friendly enough.

"Use column definitions"
Column definitions only work if the header name is a string. If JSX is returned, it must be rendered with data generated by the TanStack Table object.

"How?"
I imagine this could be implemented by adding an option getAllColumns() function to include hidden columns as well.

[DuckyCrayfish]

I'd like to mention that I would also be interested in developing a PR for this as well.