XD-1431 Support multiple AdminServers on same host

- Add Standalone HSQLDB server application
  - Have HsqlServerApplication as boot SpringApplication which loads hsql datasource and start/stop HSQLServerBean
during its context lifecycle
- Make SingleNode server start/stop HSQLServerBean during its lifecycle
- AdminServer and Container wouldn't start the HSQLServerBean (if hsqldb is choosen as batch datasource)
  - Add BatchDatasourceVerificationListener to AdminServer that checks if at least one of the batch datasource profiles is selected and exit AdminServer if not
- Remove jdbc.properties as it is not being used
- Fix tests

XD-1431 Add hsqldb-server scripts

- Add scripts and make them available inside $XD_HOME/bin/
- Make HSQLServerBean available only in singlenode and standalone hsqldb
- Fix profile name for singlenode

XD-1431 Remove profiles check on HSQLServerBean

- Since HSQLServerBean is only available in singlenode and standalone-hsqldb, we can remove
explicit check on profiles before start/stop

XD-1431 Add spring-xd-hsqldb-server project

- Create a helper project that has spring-boot, hsqldb and misc dependencies
- Move HSQLServerBean into this project
  - Create profile `hsqldbServer` and make it active for XD singlenode and standalone HSQLServer
  - Create explicit datasource with hsqldb properties to not to initiate embedded database from DataSourceAutoConfiguration
- Make this project an application
  - This will enable scripts and lib to be available following installApp gradle task and
have `copyHsqldbInstall` that will have `hsqldb` under build/dist/spring-xd
  - Set `XD_HOME` explicitly in hsqldb scripts so that the data home directory being used will have XD_HOME used
- Add this project as a dependency to `spring-xd-dirt`
  - This will enable singlenode application to use HSQLServerBean from spring-xd-hsqldb-server
  - It is expected to have the data source running prior to starting XD admin

XD-1431 Fix review comments

- Remove Datasource initializer references and use XdBatchDatabaseInitializer to
initialize batch schema along with registry schema
- Create spring-xd-batch sub project
  - Use this project to hold batch related schema and classes
  - Delete spring-xd-hsqldb-server and move the HSQLServerBean and HsqlServerApplication classes into this
  - Create HsqlDatasourceConfiguration which imports hsql-datasource
- Update hsqldb-server scripts
  - Remove XD_HOME and XD_CONFIG references and use xd.data.home to specify hsqldb data directory
- Remove the use of explicit jdbc datasource profiles
  - Delete DataSourceVerificationListener

Rename batch -> hsqldb in case of install scripts