Feature : Add plugin from a link, provide the link via flashing a QR code

[ponceta]

Describe the issue

Adding an extension with an url is nice but it will be quickly painful to add with the smartphone / tablet keyboard. Before we have a common plugin repository for all QFIELD extensions, I would suggest to add the possibility to scan a QR code to gather the extension URL.

Here was the extension URL for this specific case :

https://github.com/opengisch/qfield-geomapfish-locator/releases/download/v1.1/qfield-geomapfish-locator-v1.1.zip