Refactor: Fix missing imports, scope issues, and remove hardcoded weather data in plotting script

[lavjeetrai]

Summary:

This PR refactors the route visualization script to resolve runtime errors and improve its flexibility as a command-line tool.

Before: The script failed to execute due to missing matplotlib and graphics imports. It also relied heavily on global variables (like figurefile) inside the plotting functions, which broke modularity. Furthermore, weather data and map bounding boxes were hardcoded in the __main__ block, limiting the tool's reusability. It also contained redundant if/else logic in the plot_power_vs_dist_ratios function that executed the same code regardless of the condition.

After: * Imports & Scope Fixes: Added missing imports and refactored plotting functions to accept figurefile as an explicit argument, eliminating NameError exceptions and global scope reliance.

• CLI Enhancements: Replaced hardcoded timestamps and map coordinates with optional argparse parameters (--departure-time, --plot-time, --time-forecast, --bbox), preserving the original values as defaults. Users can now define these dynamically without modifying the script.
• Code Cleanup: Removed the redundant code block in the ratio plotting function.

Dependencies:

No new external dependencies were introduced, though matplotlib.pyplot is now explicitly imported and required for this script to run.

PR Checklist:

In the context of this PR, I:

• have (already previously) filled the 52North Contributor License Agreement and received positive feedback on this matter
• have filled the 52North Contributor License Agreement and am waiting for feedback
• provide unit tests embedded in the WRT test framework (WeatherRoutingTool/tests) that allow the simple testing of the new/modified functionalities. All (previous and new) unit tests execute without new error messages.
• ensure that the code formatter runs without errors/warnings
• ensure that my changes follow the WRT’s guidelines for contributing at the time of the contribution