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/upload-gzip.ts

@@ -0,0 +1,53 @@
+import * as fs from 'fs'
+import * as zlib from 'zlib'
+import {promisify} from 'util'
+const stat = promisify(fs.stat)
+
+/**
+ * Creates a Gzip compressed file of an original file at the provided temporary filepath location
+ * @param {string} originalFilePath filepath of whatever will be compressed. The original file will be unmodified
+ * @param {string} tempFilePath the location of where the Gzip file will be created
+ * @returns the size of gzip file that gets created
+ */
+export async function createGZipFileOnDisk(
+  originalFilePath: string,
+  tempFilePath: string
+): Promise<number> {
+  return new Promise((resolve, reject) => {
+    const inputStream = fs.createReadStream(originalFilePath)
+    const gzip = zlib.createGzip()
+    const outputStream = fs.createWriteStream(tempFilePath)
+    inputStream.pipe(gzip).pipe(outputStream)
+    outputStream.on('finish', async () => {
+      // wait for stream to finish before calculating the size which is needed as part of the Content-Length header when starting an upload
+      const size = (await stat(tempFilePath)).size
+      resolve(size)
+    })
+    outputStream.on('error', error => {
+      // eslint-disable-next-line no-console
+      console.log(error)
+      reject
+    })
+  })
+}
+
+/**
+ * Creates a GZip file in memory using a buffer. Should be used for smaller files to reduce disk I/O
+ * @param originalFilePath the path to the original file that is being GZipped
+ * @returns a buffer with the GZip file
+ */
+export async function createGZipFileInBuffer(
+  originalFilePath: string
+): Promise<Buffer> {
+  return new Promise(async resolve => {
+    const inputStream = fs.createReadStream(originalFilePath)
+    const gzip = zlib.createGzip()
+    inputStream.pipe(gzip)
+    // read stream into buffer, using experimental async itterators see https://github.com/nodejs/readable-stream/issues/403#issuecomment-479069043
+    const chunks = []
+    for await (const chunk of gzip) {
+      chunks.push(chunk)
+    }
+    resolve(Buffer.concat(chunks))
+  })
+}