configure Antora and CI workflow to support partial build (single version)

- upgrade to Antora 3.2.0-alpha.2
- upgrade release-line-extension to 1.0.0-alpha.2
- add atlas-extension
- add local autoconfig-partial-build extension
- configure deploy-docs.yml workflow to detect and set up partial build
- configure publish-docs.sh script to sync partial build

.github/actions/publish-docs.sh

@@ -1,5 +1,6 @@
 #!/bin/bash
 
+FROM=build/site
 HOST="$1"
 HOST_PATH="$2"
 SSH_PRIVATE_KEY="$3"
@@ -13,10 +14,16 @@ fi
 
 (
   set -e
+  set -f
   install -m 600 -D /dev/null "$SSH_PRIVATE_KEY_PATH"
   echo "$SSH_PRIVATE_KEY" > "$SSH_PRIVATE_KEY_PATH"
   echo "$SSH_KNOWN_HOST" > ~/.ssh/known_hosts
-  rsync --delete -avze "ssh -i $SSH_PRIVATE_KEY_PATH" build/site/ "$HOST:$HOST_PATH"
+  RSYNC_OPTS='-avz --delete'
+  if [ -n "$BUILD_REFNAME" ]; then
+    RSYNC_OPTS="-n $RSYNC_OPTS$(find $FROM -mindepth 1 -maxdepth 1 \! -name 404.html \! -name '.*' -type f -printf ' --include /%P')"
+    RSYNC_OPTS="$RSYNC_OPTS$(find $FROM -mindepth 1 -maxdepth 1 -type d \! -name _ -printf ' --include /%P --include /%P/**') --exclude **"
+  fi
+  rsync $RSYNC_OPTS -e "ssh -i $SSH_PRIVATE_KEY_PATH" $FROM/ "$HOST:$HOST_PATH"
 )
 exit_code=$?