Document how to make Scala CLI work inside firewall-ed / corporate environments

[alexarchambault]

We need to document what we have now, and find out / implement what's missing.

What we have:

• coursier mirrors
• proxy authentication

What we need:

• run from JAR archive (https://github.com/VirtusLab/scala-cli/issues/1061)
• be able to run 100% from Maven Central JARs, no binaries from GitHub release assets (like Scala.js linker, scala-cli-signing, …)
• give users the ability to use arbitrary repositories instead of Maven Central (https://github.com/VirtusLab/scala-cli/issues/1094)

[ekrich]

Hope it is ok to post this here.

> scala-cli native_props.sc

Error: java.lang.Exception: java.lang.Exception: Error while getting https://github.com/coursier/jvm-index/raw/master/index.json: download error: Caught java.io.IOException (Unable to tunnel through proxy. Proxy returns "HTTP/1.1 407 Proxy Authentication Required") while downloading https://github.com/coursier/jvm-index/raw/master/index.json
For more details, please see 'C:\Users\<user>\workspace\scripts\.scala-build\stacktraces\1660937103-9821838219452381754.log'

I believe this is the because Basic Auth doesn't work on redirect - there is one other place when Metals does a redirect that doesn't work as well. The url above becomes: https://raw.githubusercontent.com/coursier/jvm-index/master/index.json

I see the contents in the browser. Here is the original response header. location: https://raw.githubusercontent.com/coursier/jvm-index/master/index.json

[Gedochao]

This has been done in #1593, closing the ticket.

[tgodzik]

Looks like there are some issues still, so reopening