Add support for decoding tiff's with float pixel data

[brianpopow]

Prerequisites

• I have written a descriptive pull-request title
• I have verified that there are no overlapping pull-requests open
• I have verified that I am following the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules 👮.
• I have provided test coverage for my change (where applicable)

Description

This PR adds support for decoding Tiff images with float pixel data.

• Add support for decoding tiff's with 32bit float rgb pixel data
• Add support for decoding tiff's with 32bit float gray pixel data with min is black
• Add support for decoding tiff's with 32bit float gray pixel data with min is white

[codecov]

Codecov Report

Merging #1727 (556fbf8) into master (25dadda) will increase coverage by 0.04%.
The diff coverage is 94.64%.

@@            Coverage Diff             @@
##           master    #1727      +/-   ##
==========================================
+ Coverage   84.38%   84.43%   +0.04%     
==========================================
  Files         830      833       +3     
  Lines       36288    36390     +102     
  Branches     4241     4257      +16     
==========================================
+ Hits        30621    30725     +104     
+ Misses       4850     4845       -5     
- Partials      817      820       +3     

Flag	Coverage Δ
unittests	84.43% <94.64%> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...icInterpretation/BlackIsZero32TiffColor{TPixel}.cs	100.00% <ø> (ø)
...icInterpretation/WhiteIsZero24TiffColor{TPixel}.cs	0.00% <0.00%> (ø)
...icInterpretation/WhiteIsZero32TiffColor{TPixel}.cs	68.75% <50.00%> (-31.25%)	⬇️
...mageSharp/Formats/Tiff/TiffDecoderOptionsParser.cs	66.66% <82.35%> (+3.03%)	⬆️
...erpretation/BlackIsZero32FloatTiffColor{TPixel}.cs	100.00% <100.00%> (ø)
...cInterpretation/RgbFloat323232TiffColor{TPixel}.cs	100.00% <100.00%> (ø)
...cInterpretation/TiffColorDecoderFactory{TPixel}.cs	79.41% <100.00%> (+1.99%)	⬆️
...erpretation/WhiteIsZero32FloatTiffColor{TPixel}.cs	100.00% <100.00%> (ø)
...ricInterpretation/WhiteIsZero8TiffColor{TPixel}.cs	100.00% <100.00%> (ø)
src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs	89.62% <100.00%> (+0.07%)	⬆️
... and 5 more

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[JimBobSquarePants]

Can we not use BinaryPrimitives.ReadSingleBigEndian here and elsewhere?

[brianpopow]

ReadSingleBigEndian is only available with net5.0 and above

[JimBobSquarePants]

Didn't know that. Looking at the source we could only polyfill back to .NET Core 2.0 also. We'll leave it like this for now.

[JimBobSquarePants]

Great stuff 👍