Percent encoding in $ref URIs

Describe the bug
The split and bundle commands do not handle URI encoding $refs.

We used the split command on an OpenAPI spec and ended up with file such as ./paths/users_{id}.yaml. The $ref to each of those paths from the top-level file look like this:

paths:
  /users/{id}:
    $ref: paths/users_{id}.yaml

According to the spec, $ref should contain a URI, which does not permit { or } in the path - those characters should be percent-encoded.

Updating the $ref values to be percent-encoded (e.g. paths/users_%7Bid%7D.yaml) produces an error when using the bundler like the following:

Can't resolve $ref: ENOENT: no such file or directory, open '/example/openapi/paths/users_%7Bid%7D.yaml'

Expected behavior
The split command produces valid RFC3986 URIs, and the bundle command resolves $refs with percent-encoded paths.

Using OpenAPI 3+.
Redocly Version(s)
1.0.0-beta.111

Node.js Version(s)
v19.5.0

Start by reproducing the issue with the split and bundle commands using an OpenAPI 3+ document containing a path such as /users/{id}. Trace how split writes the $ref path and how bundle resolves percent-encoded paths; done means split emits valid percent-encoded URIs and bundle resolves those references successfully.