Updates to @actions/artifact package (#367)

* GZip implementation

* Optimizations and cleanup

* Update tests

* More test updates

* Update packages/artifact/src/internal-utils.ts

Co-Authored-By: Josh Gross <joshmgross@github.com>

* Clarification around Upload Paths

* Refactor to make http clients classes

* GZip fixes

* Documentation around compression

* More detailed status information during large uploads

* Pretty format

* Percentage updates without rounding

* Fix edge cases with formatting numbers

* Update packages/artifact/src/internal-utils.ts

Co-Authored-By: Josh Gross <joshmgross@github.com>

* Cleanup

* Small reorg with status reporter

* PR Feedback

* Cleanup + Simplification

* Test Cleanup

* Mock updates

* More cleanup

* Format fixes

* Overhaul to the http-manager

* Fix tests

* Promisify stats

* Documentation around implementation

* Improvements to documentation

* PR Feedback

* Remove Downloading multiple artifacts concurrently

Co-authored-by: Josh Gross <joshmgross@github.com>

packages/artifact/src/internal/http-manager.ts

@@ -0,0 +1,33 @@
+import {HttpClient} from '@actions/http-client/index'
+import {createHttpClient} from './utils'
+
+/**
+ * Used for managing http clients during either upload or download
+ */
+export class HttpManager {
+  private clients: HttpClient[]
+
+  constructor(clientCount: number) {
+    if (clientCount < 1) {
+      throw new Error('There must be at least one client')
+    }
+    this.clients = new Array(clientCount).fill(createHttpClient())
+  }
+
+  getClient(index: number): HttpClient {
+    return this.clients[index]
+  }
+
+  // client disposal is necessary if a keep-alive connection is used to properly close the connection
+  // for more information see: https://github.com/actions/http-client/blob/04e5ad73cd3fd1f5610a32116b0759eddf6570d2/index.ts#L292
+  disposeAndReplaceClient(index: number): void {
+    this.clients[index].dispose()
+    this.clients[index] = createHttpClient()
+  }
+
+  disposeAndReplaceAllClients(): void {
+    for (const [index] of this.clients.entries()) {
+      this.disposeAndReplaceClient(index)
+    }
+  }
+}