Add test showing that golangci-lint lint targets created by golangci_lint_aspect() fail to pull in dependencies.

Demonstrates aspect-build#129. Run "./lint.sh src:hello2_go" in example/ and you
should see something like this:

INFO: Invocation ID: ac22e950-5606-4161-8987-0e288bd0d046
INFO: Analyzed target //src:hello2_go (1 packages loaded, 4 targets configured).
INFO: From golangcilint src/golangcilint.hello2_go.aspect_rules_lint.report:
level=warning msg="[runner] Can't run linter goanalysis_metalinter: buildir: failed to load package : could not load export data: no export data for \"github.com/aspect-build/rules_lint/example/src/hello_helper\""
level=error msg="Running error: 1 error occurred:\n\t* can't run linter goanalysis_metalinter: buildir: failed to load package : could not load export data: no export data for \"github.com/aspect-build/rules_lint/example/src/hello_helper\"\n\n"
INFO: Found 1 target...
Aspect //tools:lint.bzl%golangci_lint of //src:hello2_go up-to-date:
  bazel-bin/src/golangcilint.hello2_go.aspect_rules_lint.report
INFO: Elapsed time: 2.526s, Critical Path: 2.24s
INFO: 2 processes: 1 internal, 1 linux-sandbox.
INFO: Build completed successfully, 2 total actions
INFO: Build Event Protocol files produced successfully.

Author: jelmer

example/src/BUILD.bazel

@@ -1,5 +1,5 @@
 load("@aspect_rules_ts//ts:defs.bzl", "ts_project")
-load("@io_bazel_rules_go//go:def.bzl", "go_binary")
+load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
 
 package(default_visibility = ["//visibility:public"])
 
@@ -39,6 +39,18 @@ go_binary(
     srcs = ["hello.go"],
 )
 
+go_binary(
+    name = "hello2_go",
+    srcs = ["hello2.go"],
+    deps = [":hello_go_helper"],
+)
+
+go_library(
+    name = "hello_go_helper",
+    srcs = ["hello_helper.go"],
+    importpath = "github.com/aspect-build/rules_lint/example/src/hello_helper",
+)
+
 cc_binary(
     name = "hello_cc",
     srcs = ["hello.cpp"],

example/src/hello2.go

@@ -0,0 +1,7 @@
+package main
+
+import "github.com/aspect-build/rules_lint/example/src/hello_helper"
+
+func main() {
+	hello_helper.Doathing()
+}

example/src/hello_helper.go

@@ -0,0 +1,6 @@
+package hello_helper
+
+// Simple function that returns an error
+func Doathing() (string, error) {
+	return "Hello from helper", nil
+}