[Artifacts] @actions/artifact list artifact functionality + download interface setup (#1495)

* actions/artifact preparation for download-artifact v4

* Test matrix strategy

* Fix needs dependency

* Improve list artifact test

* Fix typo

* Fix variables

* Cleanup download-all interfaces

* Fix tsc error

* Simplify to just name instead of artifactName

* Simplify to id instead of ArtifactId

* PR cleanup

packages/artifact/src/internal/shared/user-agent.ts

@@ -0,0 +1,8 @@
+var packageJson = require('../../../package.json')
+
+/**
+ * Ensure that this User Agent String is used in all HTTP calls so that we can monitor telemetry between different versions of this package
+ */
+export function getUserAgentString(): string {
+  return `@actions/artifact-${packageJson.version}`
+}