Support field names which aren't legal typescript identifiers.

[wing328]

based on #24741 with updated samples

See:

kubernetes-client/javascript#2962

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Summary by cubic

Generated TypeScript serializers now fall back to a field’s baseName when its JSON name is not a legal TypeScript identifier, instead of dropping the value.

• An explicitly provided name value takes precedence when both names are present.
• Updates generated samples and integration-test expectations; deserialization is unchanged.

^{Written for commit b3ffbf5. Summary will update on new commits.}

PR checklist

• Read the contribution guidelines.
• 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.
  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*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.