When decoding a compressed TIFF, truncate a too-long string instead of throwing an exception

[brianberns]

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Description

This is a proposed fix for #2983. The idea is to truncate a too-long string, rather than throw an exception. This allows ImageSharp to successfully load some problematic TIFF files.

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[brianpopow]

@brianberns Thanks for the contribution. Could you add one unit test for this case?

A test case would look like this:

[Theory]
[WithFile(Issue2983, PixelTypes.Rgba32)]
public void TiffDecoder_CanDecode_Issue2983<TPixel>(TestImageProvider<TPixel> provider)
    where TPixel : unmanaged, IPixel<TPixel> => TestTiffDecoder(provider);

This should go into Formats/Tiff/TiffDecoderTests.cs

Then you need to add the example image with the issue into tests\Images\Input\Tiff\Issues\Issue2983.tiff

The final thing you need to do is add the image to the Tiff section in TestImages.cs, for example in line 1167:

public const string Issue2983 = "Tiff/Issues/Issue2983.tiff";

[brianberns]

Done. I added the unit test and confirmed that it passes. However, I'm not very experienced with pull requests, so let me know if there are any problems.

[JimBobSquarePants]

These changes make sense to me. Thanks for your contribution. Much appreciated!