Implementation of clear() for all DialogFields (where required)

[kaczymuczy]

Environment

Bobcat version:

Greater than 2.1.0

Bobcat modules used:

• bb-aem-core
• bb-aem-65
• bb-core

Expected Behavior

All DialogField implementations have a custom implementation of the clear() method - where applicable

Actual Behavior

Only the Multifield dialog field has it's own implementation of the clear() method for now.

The DialogField Interface has a new method - clear() (https://github.com/Cognifide/bobcat/blob/master/bb-aem-core/src/main/java/com/cognifide/qa/bb/aem/core/component/dialog/dialogfields/DialogField.java) . It's used to clear up the current value of the given dialog field. Up untill now the operation of clearing the field was included in the given dialog field's setValue() method, but that has to change now that a need for separate clear() method has arrived.