Move apollo-demo, scripts/docker-quick-start and scripts/apollo-on-kubernetes out of main repository

[nobodyiam]

What's the purpose of this PR

Move apollo-demo, scripts/docker-quick-start and scripts/apollo-on-kubernetes out of main repository, see #4427.

Brief changelog

• move apollo-demo to https://github.com/apolloconfig/apollo-demo-java
• move scripts/docker-quick-start to https://github.com/apolloconfig/apollo-quick-start
• move scripts/apollo-on-kubernetes to https://github.com/apolloconfig/apollo-on-kubernetes

Follow this checklist to help us incorporate your contribution quickly and easily:

• Read the Contributing Guide before making this pull request.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit tests to verify the code.
• Run mvn clean test to make sure this pull request doesn't break anything.
• Update the CHANGES log.

[codecov-commenter]

Codecov Report

Merging #4440 (1b4ce17) into master (3e8fdc5) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #4440   +/-   ##
=========================================
  Coverage     53.57%   53.57%           
  Complexity     2692     2692           
=========================================
  Files           488      488           
  Lines         15229    15229           
  Branches       1587     1587           
=========================================
  Hits           8159     8159           
  Misses         6514     6514           
  Partials        556      556           

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[Anilople]

After remove apollo-demo/src/main/java/com/ctrip/framework/apollo/demo/spring/xmlConfigDemo/bean/XmlBean.java

Do we need to change the javadoc in

https://github.com/nobodyiam/apollo/blob/17b208d27225f7f4fe15ff0cbaf105ae47dcf507/apollo-client/src/main/java/com/ctrip/framework/apollo/spring/property/SpringValueDefinitionProcessor.java#L44

 *  <bean class="com.ctrip.framework.apollo.demo.spring.xmlConfigDemo.bean.XmlBean">

from com.ctrip.framework.apollo.demo.spring.xmlConfigDemo.bean.XmlBean to com.apolloconfig.apollo.demo.spring.bean.XmlBean?

XmlBean in https://github.com/apolloconfig/apollo-demo-java/blob/dfbd9f9c794157cbcccef7ba68d2349bef533559/spring-demo/src/main/java/com/apolloconfig/apollo/demo/spring/bean/XmlBean.java#L22 now.

[nobodyiam]

@Anilople That I think is all right as it is only used to explain what SpringValueDefinitionProcessor does - to process the placeholders in Spring XML configuration files.

To process xml config placeholders, e.g.
    <bean class="com.ctrip.framework.apollo.demo.spring.xmlConfigDemo.bean.XmlBean">
      <property name="timeout" value="${timeout:200}"/>
      <property name="batch" value="${batch:100}"/>
    </bean>