ENH: `Styler.to_string`
Adds a basic method for writing `Styler` to string using the mechanics already in place and a simplified jinja2 template. 

With the development of `Styler` in the last 18 months it has moved away from being purely a tool for adding styles and colors to HTML.

The methods: `.hide`, `.format`, `.format_index`, and the planned `set_descriptors` and `aliases` kwarg for `format_index`, allow one to fully customise the displayed items of row and column indexes, index names, levels, and the data values themselves, for output to any file-format.

This is now used for output to LaTeX as well as HTML, and it seems to be a minimal addition to add a `to_string` function giving users even further capability. (e.g. #45177)

this is cool @attack68 