[BigDecimalField] Implement the new validation behavior

[vursen]

An overview of the changes to be done

• Prevent the web component from setting itself to valid using ClientValidationUtil.
• Trigger constraint validation on client validated event
 (requires the HasClientValidation interface).
• Trigger binder validation on client validated event (requires the HasValidator interface).
• Synchronize the _hasInputValue property.
• Check for bad input (non-numeric input) during constraint validation based on the _hasInputValue property.

See DatePicker and TextField for an example.

Constraints to be tested

• required
• bad input

Additional context

There are abstract classes AbstractValidationIT and AbstractValidationPage which are supposed to be extended when testing validation for a specific component.

Part of vaadin/platform#3066

[vursen]

flow-components/vaadin-text-field-flow-parent/vaadin-text-field-flow/src/main/resources/META-INF/resources/frontend/vaadin-big-decimal-field.js

Line 22 in 851a11b

class BigDecimalFieldElement extends customElements.get('vaadin-text-field') {

The big decimal field's web component is currently maintained directly in the flow-components repo. It is based on TextField + allowedCharPattern + inputmode=decimal. However, I don't think it will be a problem. The proposed approach should work for it too.

required and bad input seem to be the only validation constraints we need to take care of.