Add option to skip saved-state, especially window-state

I'm a new user converted from sakura terminal, although most of features can be fulfilled by dconf, the new terminal window state always follow `/io/elementary/terminal/saved-state/windows-state`.

This make some use-case need extra work.

E.g. with last terminal full screened, if I just want to open another terminal to do some basic math using python, the new one is still full screened.
I need to de-fullscreen it first.

While for sakura, it never save previous terminal window state thus new terminal is always at its default size.

So it would be much better if we could have an option to allow new terminal window not to inherit window state from previous one.