Make QR code exportable as image

[SelinaBuff]

Discussed in https://github.com/inovex/scrumlr.io/discussions/3870

^{Originally posted by Resaki1 February 15, 2024} Currently, the QR code to share a session is rendered as an SVG. Right-clicking it does not give the option to save the QR code as an image (at least in Chromium). Of course you could make a screenshot, but rendering it as an image would make it easier imo