Fix Caddy download/installs

[dowlingw]

Pull Request (PR) description

Updates to installation methods:

• Support downloading 2.x releases from GitHub by generating correct release tarball name
• Fix 404 error when using the caddy download service

[dowlingw]

Looks like the caddy download endpoint no longer serves tarballs by default:

evil@destroid:~$ wget "https://caddyserver.com/api/download?plugins=http.git,http.filter,http.ipfilter&license=personal&telemetry=off" -qO caddy_linux_amd64
evil@destroid:~$ file caddy_linux_amd64 
caddy_linux_amd64: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, stripped
evil@destroid:~$ 

[dowlingw]

It occurs to me that the two install methods have different support for the class parameters here:

• Caddy API appears to return the current version only, so would ignore the $version parameter
• GitHub releases does not allow customisation of included features / modules or telemetry settings

Given the API appears to be undocumented and the user documentation points people towards the GitHub releases page, I'd suggest deprecating that install method entirely - but that seems really quite heavy handed and a major loss of functionality. Putting some fail checks in place would be a good compromise otherwise.

Have reached out to the folks at Arden labs to clarify whether there's any download api documentation available.

[dowlingw]

Sorry folks, I ran out of time to look at this - I'm going to close until I can come back to this one.