Update root project for Angular 15 support

[sagarchikane]

Things taken care of as part of this PR

• Root project package.json updates to support Angular 15 (Angular 16 release schedule) and latest Angular Material
• Project can be built with Node 18
• Many automated updates were done by following the Angular guide
• Fixed unit tests
• Fixed warning for CUSTOM_ELEMENTS_SCHEMA when running tests
• Updated Karma configurations
• Updated Github actions to fix deprecations

[Chuckv01]

Looks like CI failed when trying to run these changes: https://github.com/mobxjs/mobx-angular/actions/runs/4234842254/jobs/7360174315

Side note: Can we get https://github.com/mobxjs/mobx-angular/blob/master/.github/workflows/main.yml updated to run the project unit tests / linting?

[Chuckv01]

@sagarchikane looks like the build is failing https://github.com/mobxjs/mobx-angular/actions/runs/4242238682/jobs/7378030827

[Chuckv01]

Skips execution of unit tests on example projects

[Chuckv01]

The compare bundle sizes step is failing here as the master branch is failing to compile on the newer version of node. Shouldn't be an issue on future PRs as master will now have updated dependencies.