Extend optionst to be typed and use it to replace configt and other custom configuration objects

[chrisr-diffblue]

Currently we have both optionst and configt (plus a few other even more custom configuration options). Each has benefits - optionst is generic but un-typed, and configt is typed, but not very generic... We should expand optionst so that options are type safe, and then replace any usage of configt or other custom config objects with optionst.

[martin-cs]

I think optionst and configt are used for different things:

#1521

This is not to say that they /should/ be, just a back link to the last discussion of this.

[chrisr-diffblue]

Thanks for the link - I wasn't aware of that, so its very useful extra context.