Add TrimLineBreaks, TrimWhitespace and TrimTrailing lambdas to DefaultCodegen

[pimmerks]

We are currently in a situation with our custom templates where we are running into quite long lines with multiple if/else mustache statements.
We would like to chop up those lines, but that messes with our language's syntax (go).

With this change I would like to introduce these lambda's into the Codegen templates:

• trimLineBreaks
• trimWhitespace
• trimTrailingWithNewLine
• trimTrailing

As the C# codegen already uses some of these, I've removed them from there.

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 || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
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[wing328]

windows ci failure fixed in #21761