Added options to turn off automatically showing the signature on InsertEnter and when you begin to type.

[lafarr]

Now, if you have both auto_show_insert_enter = false and auto_show_when_typing = false, the signature help will only show if you use your defined toggle_key.

Fixes #335.

[ray-x]

I think toggle_key_flip_floatwin_setting setting address #335
if it is on and user toggle off floating windows, it should not show until user toggle it on again.

[lafarr]

I think toggle_key_flip_floatwin_setting setting address #335 if it is on and user toggle off floating windows, it should not show until user toggle it on again.

Yes, but the user still has to toggle it off each time they open neovim. This PR would make it so they can set it so it only turns on if they so choose based on the autocommands. I personally only want the signature to show if I press my toggle_key, rather than it showing automatically.