Display rendered token result in QR image text

Problem/Motivation

When the checkbox "display QR image text" is selected, the resulting display contains the pre-evaluated field string, i.e. the text "[node:url:path]" will be displayed instead of the actual value of the path component to the current node.

Steps to reproduce

1. Create a QR field.
2. Enable QR image text checkbox in field display settings.
3. Add a token such as "[node:url:path]" to the field value.
4. Use a QR code reader to confirm that the QR code contains the evaluated token value. Observe that the rendered text contains the template value, not the evaluated result.

Proposed resolution

Leverage the computation of the token text done by the QR image service.

Remaining tasks

Commit provided patch with fix.

User interface changes

Rendered result fixed; no other changes.

API changes

This patch is predicated on the QR image service providing #alt text, as done in #3177509: Add alt text to QR code images.

Data model changes

None.

Other Prerequisites

This patch also assumes that the token rendering bug has been fixed, as provided in #3156229: Fix Token rendering for [node:...] and other entity keys