Unofficial QPdfViewer (@quasar/qpdfviewer) for Vue3

This is an unofficial build for Vue3/Quasar2.

Find the official repo here: https://www.npmjs.com/package/@quasar/quasar-app-extension-qpdfviewer

This build is updated to support Vue3 composition API and Quasar 2.

Changes are discussed here: https://github.com/quasarframework/app-extension-qpdfviewer/issues/87

Expect for this to be folded back into the official extension in time, but available for teams that need it.