xunit: define codefixes for SpanAsserts

[Meir017]

The asserts defined in https://github.com/xunit/assert.xunit/blob/main/SpanAsserts.cs

• Contains(Span<char> expectedSubSpan, Span<char> actualSpan)
• Contains(Span<char> expectedSubSpan, ReadOnlySpan<char> actualSpan)
• Contains(ReadOnlySpan<char> expectedSubSpan, Span<char> actualSpan)
• Contains(ReadOnlySpan<char> expectedSubSpan, ReadOnlySpan<char> actualSpan)
• Contains(Span<char> expectedSubSpan, Span<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• Contains(Span<char> expectedSubSpan, ReadOnlySpan<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• Contains(ReadOnlySpan<char> expectedSubSpan, Span<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• Contains(ReadOnlySpan<char> expectedSubSpan, ReadOnlySpan<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• Contains<T>(Span<T> expectedSubSpan, Span<T> actualSpan)
• Contains<T>(Span<T> expectedSubSpan, ReadOnlySpan<T> actualSpan)
• Contains<T>(ReadOnlySpan<T> expectedSubSpan, Span<T> actualSpan)
• Contains<T>(ReadOnlySpan<T> expectedSubSpan, ReadOnlySpan<T> actualSpan)

---

• DoesNotContain(Span<char> expectedSubSpan, Span<char> actualSpan)
• DoesNotContain(Span<char> expectedSubSpan, ReadOnlySpan<char> actualSpan)
• DoesNotContain(ReadOnlySpan<char> expectedSubSpan, Span<char> actualSpan)
• DoesNotContain(ReadOnlySpan<char> expectedSubSpan, ReadOnlySpan<char> actualSpan)
• DoesNotContain(Span<char> expectedSubSpan, Span<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• DoesNotContain(Span<char> expectedSubSpan, ReadOnlySpan<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• DoesNotContain(ReadOnlySpan<char> expectedSubSpan, Span<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• DoesNotContain(ReadOnlySpan<char> expectedSubSpan, ReadOnlySpan<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• DoesNotContain<T>(Span<T> expectedSubSpan, Span<T> actualSpan)
• DoesNotContain<T>(Span<T> expectedSubSpan, ReadOnlySpan<T> actualSpan)
• DoesNotContain<T>(ReadOnlySpan<T> expectedSubSpan, Span<T> actualSpan)
• DoesNotContain<T>(ReadOnlySpan<T> expectedSubSpan, ReadOnlySpan<T> actualSpan)

---

• EndsWith(Span<char> expectedEndSpan, Span<char> actualSpan)
• EndsWith(Span<char> expectedEndSpan, ReadOnlySpan<char> actualSpan)
• EndsWith(ReadOnlySpan<char> expectedEndSpan, Span<char> actualSpan)
• EndsWith(ReadOnlySpan<char> expectedEndSpan, ReadOnlySpan<char> actualSpan)
• EndsWith(Span<char> expectedEndSpan, Span<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• EndsWith(Span<char> expectedEndSpan, ReadOnlySpan<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• EndsWith(ReadOnlySpan<char> expectedEndSpan, Span<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• EndsWith(ReadOnlySpan<char> expectedEndSpan, ReadOnlySpan<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)

---

• Equal(Span<char> expectedSpan, Span<char> actualSpan)
• Equal(Span<char> expectedSpan, ReadOnlySpan<char> actualSpan)
• Equal(ReadOnlySpan<char> expectedSpan, Span<char> actualSpan)
• Equal(ReadOnlySpan<char> expectedSpan, ReadOnlySpan<char> actualSpan)
• Equal(Span<char> expectedSpan, Span<char> actualSpan, bool ignoreCase = false, bool ignoreLineEndingDifferences = false, bool ignoreWhiteSpaceDifferences = false, bool ignoreAllWhiteSpace = false)
• Equal(Span<char> expectedSpan, ReadOnlySpan<char> actualSpan, bool ignoreCase = false, bool ignoreLineEndingDifferences = false, bool ignoreWhiteSpaceDifferences = false, bool ignoreAllWhiteSpace = false)
• Equal(ReadOnlySpan<char> expectedSpan, Span<char> actualSpan, bool ignoreCase = false, bool ignoreLineEndingDifferences = false, bool ignoreWhiteSpaceDifferences = false, bool ignoreAllWhiteSpace = false)
• Equal(ReadOnlySpan<char> expectedSpan, ReadOnlySpan<char> actualSpan, bool ignoreCase = false, bool ignoreLineEndingDifferences = false, bool ignoreWhiteSpaceDifferences = false, bool ignoreAllWhiteSpace = false)
• Equal<T>(Span<T> expectedSpan, Span<T> actualSpan)
• Equal<T>(Span<T> expectedSpan, ReadOnlySpan<T> actualSpan)
• Equal<T>(ReadOnlySpan<T> expectedSpan, Span<T> actualSpan)
• Equal<T>(ReadOnlySpan<T> expectedSpan, ReadOnlySpan<T> actualSpan)

---

• StartsWith(Span<char> expectedStartSpan, Span<char> actualSpan)
• StartsWith(Span<char> expectedStartSpan, ReadOnlySpan<char> actualSpan)
• StartsWith(ReadOnlySpan<char> expectedStartSpan, Span<char> actualSpan)
• StartsWith(ReadOnlySpan<char> expectedStartSpan, ReadOnlySpan<char> actualSpan)
• StartsWith(Span<char> expectedStartSpan, Span<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• StartsWith(Span<char> expectedStartSpan, ReadOnlySpan<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• StartsWith(ReadOnlySpan<char> expectedStartSpan, Span<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)
• StartsWith(ReadOnlySpan<char> expectedStartSpan, ReadOnlySpan<char> actualSpan, StringComparison comparisonType = StringComparison.CurrentCulture)