Firefox script installs x86_64 regardless of actual architecture

[alexsavage]

Description

The Firefox installation script always downloads from a URL for the x86_64 tarball:

https://github.com/ConSol/docker-headless-vnc-container/blob/4a30b26cc46d796db17e6dc962b03a3a05cc1328/src/common/install/firefox.sh#L29

Impact

Firefox does not run when the image is built for other targets, such as arm64.

Suggested solutions

• Use distribution-specific packages for Firefox (as with Chromium) when there is no binary tarball for the current architecture on releases.mozilla.org, or
• Omit Firefox from the image altogether if not targeting x86_64 to reduce installed size and not have an unusable desktop icon