switch to official Antora Plugin for Gradle

- lock version to latest release of Antora 3.1
- declare Node.js dependencies in build.gradle
- use Node.js version provided by plugin
- assign environment variables using environments property on extension block
- move group and description project properties to gradle.properties
- remove unneeded .npmrc
- upgrade to Gradle 7.5.1
- pass -q when running gradlew from Collector

lib/antora/extensions/inject-collector-config.js

@@ -1,6 +1,6 @@
 'use strict'
 
-const BASE_COMMAND = 'gradlew -PbuildSrc.skipTests=true'
+const BASE_COMMAND = 'gradlew -q -PbuildSrc.skipTests=true'
 const JVM_ARGS='-Xmx3g -XX:+HeapDumpOnOutOfMemoryError'
 const REPO_URL = 'https://github.com/spring-projects/spring-security'
 const TASK_NAME=':spring-security-docs:generateAntora'