igniteui-angular Add [toolbarTemplate] parameter to IgxGrid and IgxTreeGrid

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

I have a toolbar that I want to reuse in a bunch of different IgxGrid implementations, currently, I have to duplicate that code every time

Describe the solution you'd like

I want to reuse the same <igx-grid-toolbar> code on different IgxGrid or IgxTreeGrid, so I don't have to duplicate code on all my implementations, seems to me that the most natural way would be to use Angular content or inline template. the following example would be ideal:

<ng-template #toolbarTemplate> 
        <igx-grid-toolbar *ngIf="showToolbar" #toolbar>
                <igx-grid-toolbar-title> ... </igx-grid-toolbar-title>
                 ... custom elements
                <igx-grid-toolbar-actions *ngIf="showToolbar">
                          <igx-grid-toolbar-advanced-filtering *ngIf="allowAdvancedFiltering"> </igx-grid-toolbar-advanced-filtering>
                          <igx-grid-toolbar-hiding  (opened)="onOpenToolbarConfigUi($event)"></igx-grid-toolbar-hiding>
                          <igx-grid-toolbar-pinning  (opened)="onOpenToolbarConfigUi($event)"></igx-grid-toolbar-pinning>
                          <my-custom-button-1></my-custom-button-1>
                          <my-custom-button-2></my-custom-button-2>
                          ... more custom elements 
                </igx-grid-toolbar-actions>
        </igx-grid-toolbar>
</ng-template>
<igx-grid  #grid1 [toolbarTemplate]="toolbarTemplate"> ... and more </igx-grid>
<igx-grid  #grid2 [toolbarTemplate]="toolbarTemplate"> ... and a lot more </igx-grid>

Describe alternatives you've considered

The only alternative I currently have seems to duplicate my code, an alternative expected result for this FR could be to print the template directly and receive additional parameters using a directive:

<ng-template #toolbarTemplate> 
        <igx-grid-toolbar *ngIf="showToolbar" #toolbar>
                <igx-grid-toolbar-title> ... </igx-grid-toolbar-title>
                 ... custom elements
                <igx-grid-toolbar-actions *ngIf="showToolbar">
                          <igx-grid-toolbar-advanced-filtering *ngIf="allowAdvancedFiltering"> </igx-grid-toolbar-advanced-filtering>
                          <igx-grid-toolbar-hiding  (opened)="onOpenToolbarConfigUi($event)"></igx-grid-toolbar-hiding>
                          <igx-grid-toolbar-pinning  (opened)="onOpenToolbarConfigUi($event)"></igx-grid-toolbar-pinning>
                          <my-custom-button-1></my-custom-button-1>
                          <my-custom-button-2></my-custom-button-2>
                          ... more custom elements 
                </igx-grid-toolbar-actions>
        </igx-grid-toolbar>
</ng-template>
<igx-grid  #grid1 ...> 
        <ng-container igxToolbarGridTemplate [ngTemplateOutlet]="toolbarTemplate"></ng-container>
         ... and more
</igx-grid>
<igx-grid  #grid2 ...>
        <ng-container igxToolbarGridTemplate [ngTemplateOutlet]="toolbarTemplate"></ng-container>
         ... and a lot more
</igx-grid>

Additional context

Breaking changes or new features might need to be replicated in a lot of places, this FR might solve version upgrade issues. Also, this issue is related to this discussion where I explain a lot more my use case.