Add a test script to help debugging /open pr

The recent attempt at opening PRs for OpenSSL at
git-for-windows/git#4273 (comment)
failed to produce the correct `version` parameter: instead of the
desired `1.1.1t` it came up with `1.1_1t` (i.e. only the first
underscore was converted to a dot).

To help with debugging such issues, let's add a script that allows for
reproducing the functionality locally:

	./test-open-pr.js <url-to-issue>

will output the package name and the version that was determined from
that ticket.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

test-open-pr.js

@@ -0,0 +1,21 @@
+#!/usr/bin/env node
+
+(async () => {
+    // Expect a URL
+    const url = process.argv[2]
+    const match = url.match(/^https:\/\/github\.com\/([^/]+)\/([^/]+)\/issues\/(\d+)\/?$/)
+    if (!match) throw new Error(`Unhandled URL: ${url}`)
+    const [, owner, repo, number ] = match
+
+    const githubApiRequest = require('./GitForWindowsHelper/github-api-request')
+    const { title, body } = await githubApiRequest(
+        console,
+        null,
+        'GET',
+        `/repos/${owner}/${repo}/issues/${number}`
+    )
+
+    const { guessComponentUpdateDetails } = require('./GitForWindowsHelper/component-updates')
+    const details = await guessComponentUpdateDetails(title, body)
+    console.log(details)
+})().catch(console.log)