for-of init optimizations for grids

[ChronosSF]

Additional information (check all that apply):

• Bug fix
• New functionality
• Documentation
• Demos
• CI/CD

Checklist:

• All relevant tags have been applied to this PR
• This PR includes unit tests covering all the new code
• This PR includes API docs for newly added methods/properties
• This PR includes feature/README.MD updates for the feature docs
• This PR includes general feature table updates in the root README.MD
• This PR includes CHANGELOG.MD updates for newly added functionality
• This PR contains breaking changes
• This PR includes ng update migrations for the breaking changes
• This PR includes behavioral changes and the feature specification has been updated with them

[PavlovVasil]

@ChronosSF A found a scenario where the horizontal scrollbar does not show (but it shows in 7.2.x):

1. Run the igniteui-angular-samples repo
2. Open http://localhost:4200/samples/tree-grid/treegrid-column-hiding
3. One by one click all the checkboxes to the left and hide all possible columns - the horizontal scrollbar should disappear
4. Filter "Name" column by "ZAS" so that no records match
5. Clear the filter for "Name" by clicking the "Reset" button, then "Close" the filtering
6. In the column Hiding pane to the left, click the "Show All" button so that all hidden columns get shown again.

Result: The grid has been brought back to its initial state, but this time the horizontal scrollbar is not visible. The same happens in an igxHierarchicalGrid as well.