feat(android): smoother host-page reset after keyboard updates

> Per this discovery ([#10017 (comment)](https://github.com/keymanapp/keyman/pull/10017#discussion_r1403832330)) above... what's the right way forward?

I agree that that behaviour of relying on the picker to reload the keyboard for updates can be considered a bug.

If we detect a keyboard update/change, it should be reloaded:
a) when the system keyboard pops up, or
b) when the user switches keyboards

Some flicker is acceptable when a new version of the keyboard is installed, in either of those situations. It's just a once-off after all.

Ideally we'd also toast the new keyboard version information but that's a separate project.

_Originally posted by @mcdurdin in https://github.com/keymanapp/keyman/issues/10017#issuecomment-1830868890_

To keep things moving re #10017, we just dropped in a line to force-update the host page _immediately_ when an update completes. It's obviously not the smoothest, but it's a one-time thing per update and lets us move forward for now.