feat(ios,android): Use Swipe Pattern to Shift Keyboards

### Is your feature request related to a problem? Please describe.

Changing keyboards, which is usually toggling between an English and a non-English keyboard, seems to be the slowest of all keyboard actions, each time I wish it could be faster.

### Describe the solution you'd like

I thought you'd never ask :-) Use a swiping gesture to change between keyboards. By "swiping gesture" I mean a pattern could be drawn on the screen with a finger. On Samsung phones there is a screen unlocking feature where the user sets an unlock pattern by drawing it on the screen. Handwriting input is another example where the user can draw a shape on the screen.

The solution that I would like to see is one where the user could, for example, swipe from the lower-left corner of the keyboard area to the upper-right corner and the keyboard switches to the keyboard configured for that gesture. Then swipe in the opposite direction (upper-right to lower-left) to switch back.

So a user wanting to use swipes to change keyboards would go into Keyman settings, select a keyboard, and find a button to define a swiping action that will switch to the keyboard.

### Describe alternatives you've considered

Voice command.

### Related issues

_No response_

### Keyman apps

- [X] Keyman for Android
- [X] Keyman for iPhone and iPad
- [ ] Keyman for Linux
- [ ] Keyman for macOS
- [ ] Keyman for Windows
- [ ] Keyman Developer
- [ ] KeymanWeb
- [ ] Other - give details at bottom of form

### Keyman version

16.0.141

### Operating system

Android, iOS, iPadOS

### Device

mobile phone, tablets

### Target application

Any

### Browser

Any

### Keyboard name

Any

### Keyboard version

Any

### Language name

Any

### Additional context

It would be awesome of a swiping action could switch between the system keyboard and keyman.