feat: More robust downloading

[cpswan]

Progresses #911

- What I did

Downloader that can make use of curl or wget

- How I did it

• New function to check for commands
• Using STDERR for messages where STDOUT will get consumed by the calling function (and where they are errors the user needs to know about)

- How to verify it

I've run this on an Ubuntu VM where I removed curl and wget then put them back on

- Description for the changelog

feat: More robust downloading