zsh: added HIST_SAVE_NO_DUPS and HIST_FIND_NO_DUPS options to zsh for…

[koseduhemak]

… history configuration.

Description

Added two new config options for zsh module:

• saveNoDups: Do not write duplicate entries into the history file (setting HIST_SAVE_NO_DUPS).
• findNoDups: Do not display a line previously found in the history file (setting HIST_FIND_NO_DUPS).

Default is to unset these variables.

This allows for more fine-grained configurability of zsh behavior in terms of preserving the shell history.

Checklist

• Change is backwards compatible.

• Code formatted with ./format.

• [] Code tested through nix-shell --pure tests -A run.all or nix develop --ignore-environment .#all using Flakes.

• Test cases updated/added. See example.
  As the code is super obvious and I did not found test cases for other options like e.g. ignoreAllDups I assume that his would be fine - otherwise please let me know.

• Commit messages are formatted like

  {component}: {description}
  
  {long description}
  

  See CONTRIBUTING for more information and recent commit messages for examples.

Omitted long description, as there is nothing more to say.

• If this PR adds a new module

  • Added myself as module maintainer. See example.

Maintainer CC