Add output crs

[Hussein-Mahfouz]

This PR should close #72. It introduces a new configuration option to specify the output coordinate reference system (CRS) for various scripts. The changes ensure that all relevant data transformations and file outputs use the specified CRS from the configuration.

Configuration Changes:

• Added output_crs parameter to the config/base.toml file to specify the desired output CRS.
• Updated the Parameters class in src/acbm/config.py to include the output_crs attribute and added a property method to access it.

Script Updates:

• Modified scripts/0.1_run_osmox.py, scripts/0_preprocess_inputs.py, scripts/3.1_assign_primary_feasible_zones.py, scripts/3.2.1_assign_primary_zone_edu.py, scripts/3.2.2_assign_primary_zone_work.py, scripts/3.2.3_assign_secondary_zone.py, scripts/3.3_assign_facility_all.py, and scripts/4_validation.py to use the output_crs from the configuration for CRS transformations and file outputs.
• Modified scripts/3.1_assign_primary_feasible_zones.py and scripts/3.2.3_assign_secondary_zone.py to load correct travel_times based on config.boundary_geography (instead of hardcoded oa/ path)

Function Updates:

• Updated plot_desire_lines and plot_scatter_actual_reported functions in src/acbm/assigning/plots.py to accept a crs parameter and use it for CRS transformations.
• Update the add_locations_to_activity_chains function to use geopandas instead of a pyproj transformer, and to take in a crs parameter to convert the centroid point layer to (instead of hardcoded 4326)

[sgreenbury]

Thanks @Hussein-Mahfouz for adding this feature and the changes, as discussed I'll go ahead and merge as all looks good!