assert: add InDelta for maps with a deltas map

[julian776]

Summary

Add functionality to compare a custom delta for each map value.

Changes

Include the function to compare each delta.

Motivation

These changes now let you compare each map value with its own custom delta, instead of having to use the same for all of them.

Example usage

func TestHardcodedValues(t *testing.T) {
	expexted := map[string]float64{
		"foo": 1.0,
		"bar": 7,
		"baz": math.NaN(),
	}

	actual := map[string]float64{
		"foo": 1.01,
		"bar": 7.99,
		"baz": math.NaN(),
	}

	deltas := map[interface{}]float64{
		"foo": 0.1,
		"bar": 1,
		"baz": 0.1,
	}

	assert.InMapDeltasMapValues(
		t,
		expexted,
		actual,
		deltas,
	)
}

Related issues

Incorporate functionality #1496.

[hendrywiranto]

Hi,
I hate to break this to you but currently testify doesn't accept PR that expands the API as stated by this comment
#1500 (comment)

but I may be wrong, need to wait maintainer's response

[julian776]

I wasn't aware of this, but no problem if that's the case.