chore: add lint rule for conditional jsx rendering strict boolean checks

[pskelin]

when using conditional rendering in JSX, array length has to be treated more carefully
when ar = []

// this will render `0`
{{ ar.length && <div>content</div> }}

correct usage is to use a boolean

// this will render ``
{{ ar.length > 0 && <div>content</div> }}

There are more complicated cases however where a getter from the component is used with more logical expressions and types, so this change is adding an eslint rule and fixes other problematic spots.

FIXES: #10509