Update reCaptcha code

The reCaptcha config option does currently work relatively well, but regardless of the type of v2 reCaptcha you specify (`tickbox` or `invisible`) it always falls back to tickbox, and v3 doesn't seem to be supported at all.

I don't _think_ it'd be much work to upgrade the reCaptcha code to support both types of v2, and v3.

Start by locating the reCaptcha configuration option and the current implementation that handles v2 types. Verify how `tickbox` and `invisible` behave, then determine the changes needed for both v2 modes and v3; done means all three requested types work as configured.

Written by the indexing model from the issue text.