Add sticky headers

[Reprevise]

Is your feature request related to a problem? Please describe.
When users scroll down they lose the descriptions of the columns.

Describe the solution you'd like
There should be an option to make the header sticky.

[Dev-Owl]

That's a nice IDEA, I will look into this. Of course, pull requests are welcome to add this in.

[Dev-Owl]

Had a look into the code, this would require to change the default data table to a custom implementation. It is doable but will require a bit more work.
As of today, Flutter uses a Table that holds all rows. The header is just the row at index zero. The required change would be to move the header row out of the table. I still think it's a good idea but have to move it to a later release.

Again, feel free to fork and change this any pull requests are very welcome :)

[lublak]

also a sticky footer would be nice @Dev-Owl
Currently you only can scroll with: SingleChildScrollView
But it could help if its implemented in the table self.
So you can scroll the rows but not the header and footer (with the pagination buttons)