Fix migrations & schematics commonjs type for latest package, adjust module output

[ChronosSF]

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Additional information (check all that apply):

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

Fix: ng update migrations crash with "type": "module"

The latest ng-packagr@21.2.2 sets "type": "module" in the published package.json, causing Node.js to treat all .js files as ES modules.

[error] ReferenceError: exports is not defined in ES module scope
This file is being treated as an ES module because it has a '.js' file extension and 'igniteui-angular-samples\node_modules\igniteui-angular\package.json' contains "type": "module". To treat it as a CommonJS script, rename it to use the '.cjs' file extension.
    at igniteui-angular-samples/node_modules/igniteui-angular/migrations/common/import-helper.js:2:23
    [...]

The migrations and schematics are CommonJS so their exports = ... syntax throws exports is not defined in ES module scope. The fix adds a { "type": "commonjs" } package.json to both the migrations/ and schematics/ source directories, overriding the parent ESM setting for those subdirectories. These files are automatically copied to dist by the existing gulp tasks.
Additionally, the specific import-helper.js is a pre-compiled file to avoid a TypeScript emit converting dynamic imports to require, which is no longer needed with more modern module output modes so that is removed and updated.

[Copilot]

Pull request overview

This PR addresses ng update migration/schematics crashes when the published igniteui-angular package is treated as ESM ("type": "module"), by ensuring the migrations/ and schematics/ subdirectories are explicitly treated as CommonJS at runtime.

Changes:

• Add projects/igniteui-angular/schematics/package.json with { "type": "commonjs" }.
• Add projects/igniteui-angular/migrations/package.json with { "type": "commonjs" }.

Reviewed changes

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

File	Description
projects/igniteui-angular/schematics/package.json	Adds a nested package boundary to force CommonJS semantics for schematics runtime loading.
projects/igniteui-angular/migrations/package.json	Adds a nested package boundary to force CommonJS semantics for migrations runtime loading.

[ChronosSF]

@copilot apply changes based on the comments in this thread

[Copilot]

@copilot apply changes based on the comments in this thread

Applied. I updated /projects/igniteui-angular/.npmignore to keep migrations/package.json and schematics/package.json in the published package (!migrations/package.json, !schematics/package.json). Verified with npm pack --dry-run that both files are now included. Commit: 51d6bbe.