Feature/auto edge httpfile

[knobby-tires]

Fixes #734

What this adds:

Automatic edge handling for the HTTPFile resource. The goal is to make sure that when an HTTP file is served from a path, the file resource is properly tracked as a dependency.

How it does that:

HTTPFileResAutoEdges struct: Handles dependecy tracking by keeping a list of related resources and checks if they exist.

AutoEdges() method: If the resource is serving from a file path, it creates an automatic edge to the corresponding file resource.
If the data field is used instead, no edges are created.

How I tested:

After setting things up I ran the following curl commands

curl http://localhost:8080/test1  # Check if /test1 works
curl http://localhost:8080/test2  # Check if /test2 works
curl http://localhost:8080/dir/index  # Check if specific file works

[purpleidea]

Thanks for the patch! A few quick nits to help you get through CI and the easy stuff:

1. Missing an EOL in your example file.
2. Make everything a single commit.
3. Get rid of the go.mod changes.
4. Comments should be full sentences (capitalized/ends with punctuation) or short one-liners usually that aren't capitalized.

[knobby-tires]

Awesome, thanks for the fast reply. I will fix all of that tomorrow afternoon.

[knobby-tires]

@purpleidea I consolodated to one commit, fixed comments, removed changes to go.mod, added EOL to my example file, and made my comments more readable/professional.

[purpleidea]

(The race tests will likely fail, this is OK, but check out the other tests which should pass if there are no issues.)

[knobby-tires]

It looks like I forgot to run gofmt on http.go, I fixed that and amended it to the commit.

[purpleidea]

Your mcl file comments need the same fixups and it will also fail without tab indentation. (There's also a trailing newline at the end if you want a nit.)

[knobby-tires]

Okay got it, thanks for bearing with me. Does this look good?

[purpleidea]

CI needs a slightly different commit message, eg:

resources: Add auto edge support between http_file and file resources

And you have one vet issue. I also noticed you're missing a newline at the end of a file.