Selection handle should have platform specific behavior on mobile

[maxkatz6]

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

In current master selection handle only appears when text box is focused and it's not empty.
While matching iOS behavior, it is different from the Android, where even empty field will show selection handle, but only on second tap/click.

Stable 11.1 have yet another behavior, where selection handle is opened immediately on focus.

Describe the solution you'd like

Avalonia should support both scenarios, potentially configured by the platform via IPlatformSettings.

Describe alternatives you've considered

No response

Additional context

See #15770 PR for more details.