FilteringExpressionsTreeChange event is fired after filtering is performed

[hanastasov]

Description

FilteringExpressionsTreeChange event is fired after filtering is performed, however this event is meant to be fired before setting the expressions. ALso, the event documentation is confusing:

• igniteui-angular version: 8.2.10

Expected result

The event to be emitted before the expressions are changed, and provide the option to cancel setting new value to the expressions object.
Documentation to be corrected.

[DiyanDimitrov]

I agree the documentation is misleading and we should fix it. However the purpose of the event is to support two-way binding for the filteringExpressionsTree property and we shouldn't modify it to be cancelable. The proper way of canceling the local filtering is to use the NoopFilteringStrategy.