[Kotlin] Add escaping of $ to baseName for Kotlin generators

Created by: jyutzler

closes #10350

This eliminates compilation errors caused by generated annotations with a $, which are interpreted by the Kotlin compiler as String Templates.

Testing this was tricky because a Kotlin file with the @field Jackson annotation inexplicably compiles using the Kotlin Classloader used in KotlinSpringServerCodegenTest (even though the generated code doesn't compile in any Kotlin compiler I am aware of). The only way I could find to generate a failing test was to change @field to @get. I only did this in dataClassOptVar.mustache but this change does have a ripple effect in the generated Petstore samples. It may be prudent to revert the change to the mustache once you confirm what is happening.

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.
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