Migrate to Antora Documentation

* Use `providers.provider` for `modifiedFiles`.
This defers the looking up of `modifiedFiles` until it is used. It
also allows other tasks to be ran from the non-primary work tree.
Working in another work tree is essential for Antora which will clone
each branch/tag into a new work tree to process it.

* Migrate Structure

* Insert explicit ids for headers

* Fix image::image

* Copy default antora files

* Fix indentation for all pages

* Split files

* Generate a default navigation

* Remove includes

* Fix cross references

* Enable Section Summary TOC for small pages

* Polish nav.adoc

* Fix duplicate ids

* Escape {firstname} and {lastname}

* Remove links to htmlsingle and pdf Formats

* Fix broken links

* Disable attributes for ${debezium-version}

* Migrate to Asciidoctor Tabs

* Move to src/reference/antora

* Remove Asciidoctor Build

* deploy-docs only spring-projects

.github/workflows/deploy-docs.yml

@@ -0,0 +1,32 @@
+name: Deploy Docs
+on:
+  push:
+    branches-ignore: [ gh-pages ]
+    tags: '**'
+  repository_dispatch:
+    types: request-build-reference # legacy
+  #schedule:
+  #- cron: '0 10 * * *' # Once per day at 10am UTC
+  workflow_dispatch:
+permissions:
+  actions: write
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    if: github.repository_owner == 'spring-projects'
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+        with:
+          ref: docs-build
+          fetch-depth: 1
+      - name: Dispatch (partial build)
+        if: github.ref_type == 'branch'
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: gh workflow run deploy-docs.yml -r $(git rev-parse --abbrev-ref HEAD) -f build-refname=${{ github.ref_name }}
+      - name: Dispatch (full build)
+        if: github.ref_type == 'tag'
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: gh workflow run deploy-docs.yml -r $(git rev-parse --abbrev-ref HEAD)