Pixi support for python ezpyz apps

[CodingKaiser]

This pull request introduces support for running Python apps using Pixi, a package manager, and updates configuration and defaults to facilitate this integration. The main changes include adding a new directory for EzPyzApps, updating module defaults, and modifying the Python app runner logic to optionally use Pixi instead of Conda.

Pixi integration and Python app execution:

• Updated run_PyApp in global_variables.rb to support running Python apps via Pixi when pixi_enabled is true, constructing the command with pixi run and using the new ezpyz_dir configuration. The method now accepts a pixi_enabled parameter to choose between Pixi and Conda environments.
• Changed the commands method in EzPyzExampleApp.rb to call run_PyApp with pixi_enabled: true instead of using a Conda environment, enabling Pixi-based execution for this example app.

Configuration and default values:

• Added config.ezpyz_dir to the production environment configuration, specifying the location of EzPyzApps for use with Pixi.
• Set default modules in EzPyzExampleApp.rb to include Tools/seqtk and Dev/pixi, reflecting the new Pixi integration.