feat: add migration for self-closing tags

[eneajaho]

Angular supports self-closing tags. This means that you can write tags like <app-component /> instead of <app-component></app-component>.
This is a feature that was introduced in Angular 16.

To run the migration you can run:

ng g ngxtension:convert-to-self-closing-tag

Closes #395

[tomer953]

FYI, angular-eslint has implemented this as eslint rule with auto fix.
I would consider adding a reference or "tip" in the util docs, if someone wants to add this rule to avoid closing-tags after the migration.