feat(h-grid): update adv filtering schema on row expand

[igdmdimitrov]

Closes #15827
Closes #15908

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 (test guidelines)
• This PR includes API docs for newly added methods/properties (api docs guidelines)
• 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 (migrations guidelines)
• This PR includes behavioral changes and the feature specification has been updated with them

[gedinakova]

@igdmdimitrov There's an issue when expanding inner levels:

1. Load HGrid Advanced Filtering dev demo
2. Expand the first record, then its first child

Result: The following error is thrown in the console:
grid-base.directive.ts:7198 ERROR TypeError: Cannot set properties of undefined (setting 'fields')
at _IgxHierarchicalGridComponent.updateRootGridSchema (hierarchical-grid.component.ts:1292:25)
at Object.next (hierarchical-grid.component.ts:686:18)
at _IgxHierarchicalGridComponent.autogenerateColumns (grid-base.directive.ts:7198:35)

Expected result: No errors

[gedinakova]

As currently setup, the AF dialog cannot be open in HGrid Advanced Filtering dev demo. The following console error is thrown:
ERROR TypeError: Cannot read properties of undefined (reading 'pipeArgs')
at _IgxQueryBuilderTreeComponent.getFormat (query-builder-tree.component.ts:1413:58)
at IgxQueryBuilderTreeComponent_ng_template_11_Conditional_0_Conditional_1_Conditional_10_Conditional_2_Conditional_1_Conditional_1_Template (query-builder-tree.component.html:211:45)
at executeTemplate (debug_node-Dn-GvQJo.mjs:7142:9)
at refreshView (debug_node-Dn-GvQJo.mjs:8887:13)
at detectChangesInView (debug_node-Dn-GvQJo.mjs:9107:9)
at detectChangesInViewIfAttached (debug_node-Dn-GvQJo.mjs:9067:5)
at detectChangesInEmbeddedViews (debug_node-Dn-GvQJo.mjs:9024:13)
at refreshView (debug_node-Dn-GvQJo.mjs:8916:9)
at detectChangesInView (debug_node-Dn-GvQJo.mjs:9107:9)
at detectChangesInViewIfAttached (debug_node-Dn-GvQJo.mjs:9067:5)

[gedinakova]

@igdmdimitrov In the generateSchema method, please uncomment the label & header (I thought this was fixed at some point, but apparently not).

[gedinakova]

We need a Changelog update for this change.