fix(elements): strip Blazor externalObject from expression tree events - 20.1.x

[IMinchev64]

Closes https://github.com/Infragistics-Developer-Tools/dev-tools/issues/3208

Description

Motivation / Context

Type of Change (check all that apply):

• Bug fix
• New functionality
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactoring (no functional changes)
• Documentation
• Demos
• CI/CD
• Tests
• Changelog
• Skills/Agents

Component(s) / Area(s) Affected:

How Has This Been Tested?

• Unit tests
• Manual testing
• Automated e2e tests

Test Configuration:

• Angular version:
• Browser(s):
• OS:

Screenshots / Recordings

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
• Accessibility (ARIA, keyboard navigation, focus management) has been verified

[Copilot]

Pull request overview

This PR addresses Blazor-injected externalObject values leaking into expression-tree-related event payloads, which can break comparison/serialization scenarios in Ignite UI Angular and the Elements strategy layer (issue #3208).

Changes:

• Ignore externalObject during Query Builder tree equality checks to prevent unnecessary root recreation / stringify failures.
• Strip externalObject from expression-tree-related output event args in the Angular Elements custom strategy.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
projects/igniteui-angular/src/lib/query-builder/query-builder-tree.component.ts	Adds externalObject to the JSON stringify replacer ignore list used for root group comparison.
projects/igniteui-angular-elements/src/app/custom-strategy.ts	Adds expression-tree event handling that removes condition.externalObject from emitted trees before dispatching events.