eslint rule enforcing usage of push pipe instead of async

[frontend-specialisten]

Our recommendation is using the push pipe instead of the async pipe. This can be enforced by creating a custom eslint rule and thereby giving the developers quicker feedback.

Acceptance criteria:

• [ ] Create custom eslint rule
• [ ] Add docs to "getting started" how to make eslint linting HTML files in VsCode

Technical notes: https://nx.dev/packages/linter/generators/workspace-rule