Angular18 standalone sample app

[jo-arroyo]

Angular sample application using MSAL Angular v3 and Angular 18.0.0-rc.1.

Documentation updates confirming MSAL Angular's support of Angular 18 will come in another PR when Angular 18 is released.

[ProPotential]

angular18 standalone sample app does not build:
npm install
npm WARN EBADENGINE Unsupported engine {
npm WARN EBADENGINE package: '@azure/[email protected]',
npm WARN EBADENGINE required: { node: '10 || 12 || 14 || 16 || 18' },
npm WARN EBADENGINE current: { node: 'v20.15.1', npm: '9.8.1' }
npm WARN EBADENGINE }