Java adds security to ApiClient

[spacether]

• Generates one class for each security entry (security requirement object)
• Generates one XSecurityInfo class per security key, allows saving instances of all security requirement objects. Public builder requires that a minimum of 1 security requirement object is defined.
• Integrates XSecurityInfo classes into the ApiConfiguration class
• This allows security configuration info to be set in the ApiConfiguration class, which will be used later

Future Work

• add documentation for Java root security

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  mvn clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh
  

  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/python*.
  For Windows users, please run the script in Git BASH.