SummaryOperand with additional filter

[RolandTa]

Is your feature request related to a problem? Please describe.

I want to create a custom summaryOperand with an option to apply a filter of the values. the filter should only affect the summary of a specific summary result.

See https://stackblitz.com/edit/angular-m5qtcr
The usecase would be to show two sum values for UnitsInStock. One is the total of all records and one is the total of all discontinued articles.

Describe the solution you'd like

Extend the IgxSummaryOperand.operate method to allow access to the underlying rowData so a complex custom summary can be applied individually.

Describe alternatives you've considered

None

Additional context

https://stackblitz.com/edit/angular-m5qtcr

[zdrawku]

Same as #5754