Java, schema documentation improvements for strings [breaking]

[spacether]

Java, schema documentation improvements for strings

• adds date example
• adds date-time example
• adds uuid example
• adds number example
• adds pattern example

Breaking Change with Fallback

• CodegenPatternInfo.pattern had its type changed from String to CodegenText to allow python to use the original value and for Java to use the codeEscaped value, and for example generation to use the original
• To fix you templates use {{pattern.original}} to keep accessing the original string

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.