AV-57335 POC config to antora-ify sources

See couchbase/docs-site#699

This extension uses the config in antora.yml to call
getafix.sh and copy relevant sources into a modules/
structure.

(This is POC, so I've just copied some random sources)

Author: osfameron

asterixdb/asterix-doc/antora.yml

@@ -0,0 +1,8 @@
+name: analytics
+version: true
+ext:
+  collector:
+    run:
+      command: asterixdb/asterix-doc/getafix.sh
+    scan:
+      dir: build

asterixdb/asterix-doc/clean.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+rm -rf build/

asterixdb/asterix-doc/getafix.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+cd $(dirname $0)
+
+./clean.sh
+
+mkdir -p modules/asterixdb/partials/
+
+cp -r src/site/markdown/ modules/asterixdb/partials/
+
+