feat(keyboard): Animate webview on keyboard open / close

## Feature Request

### Plugin
Keyboard

### Description of current problem
When using `KeyboardResize.Body` as option, cf https://capacitorjs.com/docs/apis/keyboard#keyboardresize, the interface has a whole app glitch:

ON OPENING
- the keyboard opens
- then the webview height is set to a lower height, creating a content instant "pop"

ON CLOSING
- the keyboard closes, creating an empty area (cf the red area on the gif bellow)
- the webview height is 100%, but expands instantly as a glitch


### Platform(s)
iOS
Android

### Preferred Solution
Make the webview height follow the keyboard height, or change instantly when keyboard begins to open.

### Additional Context
Similar never resolved issue with Corodva: https://github.com/cjpearson/cordova-plugin-keyboard/pull/22