Fix unpack of layers on Mapbox mode to include custom fields

[PHKenny]

Add support for custom Mapbox styles by including mapboxCustomStyleId and mapboxCustomUsername in ThemedTileLayer. Update version to 7.5.18.

[github-actions]

📋 Changelog Summary

This PR includes the following changes:

🐛 Bug Fixes

• unpack of layers on Mapbox mode does not include the custom fields (2a3ce1d by @PHKenny)

📊 Diff Stats

Metric	Count
📄 Files changed	4
🟢 Insertions	$\color{green}\textsf{+12}$
🔴 Deletions	$\color{red}\textsf{-6}$

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[github-actions]

📊 Test Coverage Report

🎯 Dart/Flutter

Metric	Value
Coverage	11.1%
Lines covered	10792 / 127
Lines missing	-10665

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