Avoid quoting newlines

[jnyrup]

#2144 (comment) pointed out that we incorrectly added Environment.Newline as an argument, which due to how StringValueFormatter format strings, adds double quotes around the newline.
This bug was added in #712 by yours truly.

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[coveralls]

Pull Request Test Coverage Report for Build 4909143736

• 37 of 37 (100.0%) changed or added relevant lines in 6 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.001%) to 97.204%

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Files with Coverage Reduction	New Missed Lines	%
Src/FluentAssertions/ObjectAssertionsExtensions.cs	3	96.05%

Totals
Change from base Build 4907980274:	-0.001%
Covered Lines:	12867
Relevant Lines:	13109

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💛 - Coveralls

[dennisdoomen]

Wouldn't it be easier (and cleaner) to have StringValueFormatter handle Environment.Newline better?

[jnyrup]

Wouldn't it be easier (and cleaner) to have StringValueFormatter handle Environment.Newline better?

Are you imagining not quoting arguments to StringValueFormatter if they are equal to Environment.Newline?
A naïve implementation of that won't work if the subject or expectation is Environment.Newline.

[dennisdoomen]

A naïve implementation of that won't work if the subject or expectation is Environment.Newline.

Yeah, it's probably going to be a little hard to read a newline if it's not quoted.