Support Conversion in MeasureUnit.

[younies]

Add ConversionInfoToBase and update MeasureUnit for unit conversion support

• Introduced ConversionInfoToBase class to encapsulate conversion details to base units.
• Enhanced MeasureUnitImpl to include conversion information and updated the forIdentifier method to initialize it.
• Added getConversionInfoToBase method in ConversionRates for retrieving conversion details.
• Implemented conversion logic in MeasureUnit for converting between units, including handling of incompatible units with a new UnitsIncompatibleException.
• Updated related classes to support the new conversion structure and ensure compatibility checks during conversions.

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