fix(select): support igx-select-item inside nested @for/@if control flow blocks - 20.1.x

[Zneeky]

Closes #

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

[Copilot]

Pull request overview

This PR fixes igx-select rendering when igx-select-item (and groups) are placed inside nested Angular control-flow blocks (e.g. @for + @if/@else), where Angular content projection can fail to place nodes into the select’s scroll container.

Changes:

• Add DOM-reconciliation logic in IgxSelectComponent to move unprojected select items/groups into the scroll container, preserving template order.
• Add unit tests covering nested control flow scenarios for both plain items and grouped items.
• Update the sample app to expose a Select sample route and include a demo section reproducing the nested control flow scenario.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/app/select/select.sample.ts	Adds sample data used by the new nested control-flow select demo.
src/app/select/select.sample.html	Adds a demo <igx-select> using @for with nested @if/@else.
src/app/app.routes.ts	Registers the Select sample route.
src/app/app.component.ts	Adds “Select” to the sample app navigation.
projects/igniteui-angular/src/lib/select/select.component.ts	Implements moveItemsToScrollContainer() and invokes it on init and content changes.
projects/igniteui-angular/src/lib/select/select.component.spec.ts	Adds coverage for nested control-flow items/groups and dynamic changes.