Add basic auth support

Closes gh-4

README.adoc

@@ -226,6 +226,21 @@ antora:
     - url: https://repo.example.com/com/example/myproject/my-project-docs/${version}/my-project-docs-${version}-${name}.zip
 ----
 
+You can also configure basic auth by using `username` and `password` configuration:
+
+.antora-playbook.yml
+[,yaml]
+----
+antora:
+  extensions:
+  - require: '@springio/antora-zip-contents-collector-extension'
+    version_file: gradle.properties
+    username: me
+    password: ${env.MY_SECRET_PASSWORD}"
+    locations:
+    - url: https://repo.example.com/com/example/myproject/my-project-docs/${version}/my-project-docs-${version}-${name}.zip
+----
+
 
 
 === Local Files

packages/antora-zip-contents-collector-extension/lib/index.js

@@ -183,7 +183,13 @@ function register ({ config, downloadLog }) {
     for (const location of locations) {
       if (considerLocation(location, versionClassification)) {
         const url = resolvePlaceholders(location.url, locationVariables)
+        const username = location.username || config.username
+        const password = location.password || config.password
         const httpHeaders = { ...config.httpHeaders, ...location.httpHeaders }
+        if (username || password) {
+          const credentials = Buffer.from(`${username ?? ''}:${password ?? ''}`).toString('base64')
+          httpHeaders.Authorization = `Basic ${credentials}`
+        }
         if (['http:', 'https:'].some((prefix) => url.toLowerCase().startsWith(prefix))) {
           try {
             return await download(name, url, httpHeaders, downloadCacheDir, downloadLog)

packages/antora-zip-contents-collector-extension/test/zip-contents-collector-extension-test.js

@@ -455,6 +455,32 @@ describe('zip contents collector extension', () => {
       })
     })
 
+    it('should download zip and collect files with global username / password', async () => {
+      process.env.MY_PASSWORD = 'secret'
+      const extensionConfig = () => ({
+        username: 'admin',
+        password: 'secret',
+        locations: [{ url: `http://localhost:${httpServerPort}/\${name}.zip` }],
+      })
+      const componentConfig = { include: ['start-page'] }
+      await runScenario({
+        repoName: 'test-at-root',
+        extensionConfig,
+        componentConfig,
+        zipFiles: ['start-page'],
+        httpPath: '/',
+        httpUsers: { admin: 'secret' },
+        before: ({ contentAggregate }) => {
+          expect(contentAggregate).to.have.lengthOf(1)
+          expect(contentAggregate[0].files).to.be.empty()
+        },
+        after: ({ contentAggregate }) => {
+          expect(contentAggregate[0].files).to.have.lengthOf(1)
+          expect(contentAggregate[0].files[0].src.path).to.equal('modules/ROOT/pages/index.adoc')
+        },
+      })
+    })
+
     it('should update component metadata from antora.yml file, if found in root', async () => {
       const extensionConfig = () => ({
         locations: [{ url: `http://localhost:${httpServerPort}/\${name}.zip` }],