Add tests for @sentry/angular

[AbhiPrasad]

Currently https://github.com/getsentry/sentry-javascript/tree/master/packages/angular has no tests - we should change that.

[vladanpaunovic]

@onurtemizkan is there any update on this?

[onurtemizkan]

@vladanpaunovic -- I'm planning to open a PR in a few days.