Add Point to MeasurementUnit Enum

[ikramulhaque-iron]

Title

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Description

Model IronSoftware.Drawing.Rectangle contains a Property named MeasurementUnit. This MeasurementUnit enum contains only 2 values. (Pixel and Millimeters). And the default value is considered as Pixel. But, in PDF we use another type of Measurement unit which is called Point (1 Point = 1 Inch / 72). So we have to add one more enum value Point to the MeasurementUnit enum.

Fixes #(PDF-1489)
Fixes #(PDF-1689)
If this PR addresses an existing issue, mention the issue number here.

Type of change

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• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 🏗️ Internal/structural update (non-breaking change that improves code quality, organization, or performance)
• 📚 This change requires a documentation update
• 🚀 DevOps build chain modification for release
• 🤖 DevOps build chain modification for CI

How Has This Been Tested?

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• My code follows the style guidelines of this project
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• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
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Additional Context

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[ikkyuland]

need to update
public Rectangle ConvertTo(MeasurementUnits units, int dpi = 96) too right?

[ikkyuland]

Nice! thanks for add unit-tests and update doc!

Sorry, could you please also update RectangleF class too?