Support custom Gromacs executable path and working directory

[mcardZH]

Feature suggestions for GromacsWrapper:

1. Custom Gromacs executable path:
   Allow users to specify the path to the Gromacs executable, rather than relying on the default. This is especially useful when multiple versions of Gromacs are installed and users need to select a specific version for different workflows or compatibility reasons.

2. Custom working directory:
   Allow users to set a custom working directory, so all input and output files generated by Gromacs can be redirected to a specified location. This improves file management, especially for batch jobs or automated pipelines, and helps prevent files from being scattered across different directories.

Implementing these features would greatly enhance the flexibility for users managing multiple Gromacs installations and complex workflows.