suggestion: implementation of click and hold behavior

To interact correctly with `MDSwitch` widget, I needed to have a click and hold behavior in order to change its state:
`click_on` and `wait_click` methods from client are not working in this case, so I found a tricky workaround for this that I would like to share:

I managed to do this using `wait_drag` client method, putting as selector the Thumb and as target the same, specifying a proper duration and timeout, in this way I was able to reproduce desired behavior.

Here it is the code I wrote:
```
switch_locator = f'//MDSwitch[@name~="{provider_name}"]/Thumb[0]'
cli.wait_drag(switch_locator, switch_locator, duration=3, timeout=30)
```

Maybe it could be useful to implement a `click_hold_on` or a `wait_click_hold` method inside client that can use this "trick".
What do you think?

Start by tracing the client methods `click_on`, `wait_click`, and `wait_drag`, using the reported `MDSwitch` Thumb selector and the supplied workaround as the behavioral reference. Determine where a click-and-hold client method belongs and verify that it supports the stated duration and timeout behavior; the issue does not mention a specific file or test to run.

Written by the indexing model from the issue text.