Updates rollup version

[walmazacn]

Description

Changes proposed in this pull request:

• updates rollup version

Related issue(s)

Resolves #3953 | See also #3955

[ndricimrr]

I think we can use this PR to update rollup wherever possible that includes the following:

• client-frameworks-support/client-support-angular
• core
• test/e2e-test-application
• website/docs
• core/examples/luigi-example-angular
• core/examples/luigi-example-vue
• core/examples/luigi-example-angular

I think rollup is used there but as a "child" dependency of another dependency. You can find these if you search "rollup" and it will show up in package-lock.jsons that you can use to find out which parent dependency has it as a child and update that. I think this issue is quite popular and many other packages might have already updated rollup internally.

Example: @angular-devkit/build-angular depends on "rollup": "4.20.0", on our luigi-example-angular and it was already bumped on their side here

In case some pacakge that we use hasn't updated their rollup dep then you can note it down in the PR description. (Maybe we can also fix it with "overrides")