Apply style and explode values from encoding for form-encoded request body parameters

Created by: harmony7

This PR adds support for the style and explode values on the encoding object onto request body parameters that are submitted as application/x-www-form-urlencoded or multipart.

The Encoding Object allows the specification of style and explode similar to how they can be applied to operation parameters.

There has already existed code that would apply contentType from this Encoding Object, but this was the only value that was being applied. This PR renames that function from setParameterContentType to setParameterEncodingValues, and now also applies style and explode as appropriate.

I've added tests to DefaultCodegenTest.testRequestBodyContent() against some new definitions in resources/3_0/content-data.yaml to show that these work.

This should fix issues such as #3781 and #11256.

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:

  ./mvnw 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/java*. For Windows users, please run the script in Git BASH.