feat(ui5-time-picker): introduce open property

[hinzzx]

Add open property to replace the openPicker method in the ui5-time-picker component.

BREAKING CHANGE: Removed openPicker(), closePicker(), and isOpen() methods.

Before, the ui5-time-picker popover could be opened and closed by calling openPicker() and closePicker():

const timePicker = document.getElementById("exampleID");
timePicker.openPicker();
timePicker.closePicker();

Now, the popover is opened and closed by setting the open property to true or false:

const timePicker = document.getElementById("exampleID");
timePicker.open = true;
timePicker.open = false;

Related to: #8461

[vladitasev]

Please add an event every time you introduce a user-controlled property: #9076