Update version string management

[HylianFreddy]

This changes how the version string displayed in the app is computed, making the process more automatic.

The new bash script write_version.sh generates a header file with a macro for the version string, handling both the GitHub Action inputs and the local build:

• for Release versions, the string will be like 'vX.Y', without the commit SHA which was previously included;
• for Nightly versions, it will be 'Nightly-xxxxxx' with the commit SHA (previously it was 'vX.Y-xxxxxx');
• for local builds, it will be 'dev-xxxxxx' with the commit SHA, instead of the previous hardcoded 'v4.0-develop'.

A couple of issues are also fixed:

• the linux_build_rando.sh script will now error out if a build step fails, so the Action will properly terminate.
• the descriptions for Release versions will show the correct QR codes images (previously the URL was mistakenly including the word 'Nightly')