Interface HasLabel for components with integrated label

[probert94]

Description

I would like to be able to get the value of the integrated label for different components like TextField, DatePicker and so on. However, those components don't share a common interface with the methods getLabel and setLabel at the moment.
There are already interfaces for components with a text (HasText), a value (HasValue) and so on. In my opinion it would be very helpfull to have a similar interface for components with an integrated label too (maybe HasLabel?).

A few components, which should implement this interface:

• CheckBox
• CheckBoxGroup
• ComboBox
• CustomField
• DatePicker
• DateTimePicker
• RadioButtonGroup
• Select
• Tab
• AbstractNumberField
• BigDecimalField
• EmailField
• PasswordField
• TextArea
• TextField
• TimePicker

[mvysny]

Thank you very much for letting us know! This is probably a duplicite of #3241 .

[probert94]

@mvysny thank you for letting me know, I didn't noticed that issue.
Closing this in favor of #3241