Provide a way to get ID maps from plot parameters on the Model class

[pshriwise]

Description

This pull request introduces a new method, id_map, to the openmc.Model class for generating ID maps based on slice plot parameters, along with corresponding unit tests to validate its functionality. The changes enhance the modeling capabilities and ensure robust testing for the new feature.

It is also possible to do this using the openmc.lib module directly, but it is tedious and requires direct use of an internal object, openmc.lib.__PlotBase.

Enhancements to openmc.Model:

• Added id_map method: The id_map method generates a NumPy array representing IDs for cells, cell instances, and materials based on plot parameters. It initializes the model if not already initialized and ensures proper finalization after execution.

Unit Tests for id_map:

• Added test_model_id_map function: This test verifies the correctness of the id_map method by checking the array's shape, data type, and validity of cell/material IDs. It also ensures proper initialization and finalization behavior depending on the model's state.

Checklist

• [] I have performed a self-review of my own code
• I have run clang-format (version 15) on any C++ source files (if applicable)
• I have followed the style guidelines for Python source files (if applicable)
• I have made corresponding changes to the documentation (if applicable)
• I have added tests that prove my fix is effective or that my feature works (if applicable)