chore(changelog): Add short description for groupRecord in changelog (#12478)

* chore(changelog): add short description for groupRecord

* chore(changelog): fix groupRecord parameter desctiption

* chore(grid-summary): add exposed groupRecord property in template

* chore(API doc): pass groupRecord in result object

Author: Katrin

CHANGELOG.md

@@ -18,6 +18,8 @@ All notable changes for each version of this project will be documented in this
         * - `IgxColumnComponent` - `ColumnType` (for example the column parameter in `igxFilterCellTemplate`)
         * - `IgxGridCell` - `CellType` (for example the cell parameter in `igxCell` template)
 
+    - A new `groupRecord` parameter has been exposed in `operate` method, that is an `IGroupByRecord` object describing the grouped row in case grouping is applied.
+
     - `excelStyleHeaderIconTemplate` - Gets/Sets the excel style header icon.
     - `groupRowTemplate` - Gets/Sets the template reference for the group row.
     - `headSelectorTemplate` - Gets/Sets the header row selector template.

projects/igniteui-angular/src/lib/grids/summaries/grid-summary.ts

@@ -61,7 +61,7 @@ export class IgxSummaryOperand {
      *   constructor() {
      *     super();
      *   }
-     *   public operate(data: any[], allData: any[], fieldName: string): IgxSummaryResult[] {
+     *   public operate(data: any[], allData: any[], fieldName: string, groupRecord: IGroupByRecord): IgxSummaryResult[] {
      *     const result = [];
      *     result.push({
      *       key: "test",
@@ -151,8 +151,8 @@ export class IgxNumberSummaryOperand extends IgxSummaryOperand {
      *   constructor() {
      *     super();
      *   }
-     *   public operate(data: any[], allData: any[], fieldName: string): IgxSummaryResult[] {
-     *     const result = super.operate(data, allData, fieldName);
+     *   public operate(data: any[], allData: any[], fieldName: string, groupRecord: IGroupByRecord): IgxSummaryResult[] {
+     *     const result = super.operate(data, allData, fieldName, groupRecord);
      *     result.push({
      *       key: "avg",
      *       label: "Avg",
@@ -244,8 +244,8 @@ export class IgxDateSummaryOperand extends IgxSummaryOperand {
      *   constructor() {
      *     super();
      *   }
-     *   public operate(data: any[], allData: any[], fieldName: string): IgxSummaryResult[] {
-     *     const result = super.operate(data, allData, fieldName);
+     *   public operate(data: any[], allData: any[], fieldName: string, groupRecord: IGroupByRecord): IgxSummaryResult[] {
+     *     const result = super.operate(data, allData, fieldName, groupRecord);
      *     result.push({
      *       key: "deadline",
      *       label: "Deadline Date",