Rename pageResourceId to instanceResourceId in LiftRules.

Also drop a comment on it indicating what it’s for, and move it
closer to its usage spot.
Add instance- prefix to instance resource id.

This makes it clearer what it is when looking at the output of
lift:with-reosurce-id (before it looked like a function binding),
and also ensures that we won’t warn you about an unbound
function name when using with-resource-id.
Merge pull request #1521 from lift/asc-issue-1521

Fix the unexpected WARN while using `with-resource-id` by making instance IDs their own thing.