Url support for source bundles

[DamGouz]

It would be great if source bundles had support for fetching source files from a url, rather than from a file inside the zip file.
That way, we can fetch sources directly from Perforce by using Swarm urls, even though Perforce is not supported by sentry.

[Swatinem]

In theory we have the ability to download individual source files for source context now, initially developed for the .NET source-link: #1103

There is also a long standing feature request to allow downloading the source code from debuginfod symbol servers:
#445

In theory we could add a new "filter" for symbol servers that contain source code, and a couple of special path schemes how to find that source code. However that would be a bigger feature, also tying into the whole external symbol server configuration in sentry itself.

[DamGouz]

But what about adding that exact same source-link feature in source bundles, as we don't always have control over the event context.

[Swatinem]

I would assume the SourceBundle manifest would need to be adapted for that, probably with some non-trivial changes.
Not to mention than you would have to somehow upload such a special SourceBundle via sentry-cli somehow…

[Swatinem]

As discussed in chat, I believe all the missing pieces here are implemented.

We have put in sourcelink support into the SourceBundle manifest format, however it is currently only aimed at "power users", as it requires manually building a SourceBundle.

Support for authentication was also added, using the same form that we use for JS scraping.