[csharp][generichost] Allow property accessor overrides

[devhl-labs]

If the api returns poorly named properties or redundant properties, this gives client library authors a way to hide or rename properties. For example, the clash of clans api returns properties MemberList (array) and Members (int). In C#, MemberList isn't a great name, and Members is redundant because the count can be accessed via the list.

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.

[cubic-dev-ai]

All reported issues were addressed across 99 files

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