Scan0 with partial lock

Scan0 behaves in mysterious ways when you don't lock the entire bitmap.

It will point at the top left corner of the locked region. You should only write data for the parts of the rows you locked. But each row that you should write to is separated by Stride number of bytes.

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* ID: ccecca6b-4d3a-4b28-a10f-14815813886d
* Version Independent ID: 1a90c36c-f956-f3a5-677e-f3ff597f28a2
* Content: [BitmapData.Scan0 Property (System.Drawing.Imaging)](https://docs.microsoft.com/en-us/dotnet/api/system.drawing.imaging.bitmapdata.scan0?view=netframework-4.7.2)
* Content Source: [xml/System.Drawing.Imaging/BitmapData.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System.Drawing.Imaging/BitmapData.xml)
* Product: **dotnet-api**
* GitHub Login: @dotnet-bot
* Microsoft Alias: **dotnetcontent**