rework the search indexing process

- reconfigure the docsearch scraper to store component and version for each res
- switch from the Docker image to a resuable GitHub Action
- add publish-docsearch-config extension to transform Handlebars into YAML

lib/antora/extensions/publish-docsearch-config.js

@@ -0,0 +1,28 @@
+'use strict'
+
+const fsp = require('node:fs/promises')
+const ospath = require('node:path')
+
+/**
+ * An Antora extension that generates the docsearch config file from a Handlebars template and publishes it with the
+ * site, where the scraper job can retrieve it.
+ */
+module.exports.register = function ({ config: { templatePath = './docsearch/config.json.hbs' } }) {
+  const expandPath = this.require('@antora/expand-path-helper')
+  const handlebars = this.require('handlebars').create()
+  handlebars.registerHelper('eq', (a, b) => a === b)
+  handlebars.registerHelper('and', (a, b) => a && b)
+
+  this.on('beforePublish', async ({ playbook, contentCatalog, siteCatalog }) => {
+    templatePath = expandPath(templatePath, { dot: playbook.dir })
+    const templateSrc = await fsp.readFile(templatePath, 'utf8')
+    const templateBasename = ospath.basename(templatePath)
+    const template = handlebars.compile(templateSrc, { noEscape: true, preventIndent: true, srcName: templateBasename })
+    const components = contentCatalog.getComponentsSortedBy('name').filter((component) => component.latest.version)
+    const stopPages = contentCatalog.getPages((page) => {
+      return page.out && ('page-archived' in page.asciidoc.attributes || 'page-noindex' in page.asciidoc.attributes)
+    })
+    const compiled = template({ components, site: playbook.site, stopPages })
+    siteCatalog.addFile({ contents: Buffer.from(compiled), out: { path: 'docsearch-config.json' } })
+  })
+}