Relax IsEmpty, IsNotEmpty and Coalesce constraint from comparable to any

[CorentinClabaut]

closes #218

[samber]

Much much slower

import (
	"reflect"
	"testing"
)

func IsEmptyComparable[T comparable](v T) bool {
	var zero T
	return zero == v
}

func IsEmptyReflect[T any](v T) bool {
	return reflect.ValueOf(&v).Elem().IsZero()
}

func BenchmarkMap(b *testing.B) {
	b.Run("IsEmptyComparable(42)", func(b *testing.B) {
		for n := 0; n < b.N; n++ {
			_ = IsEmptyComparable(42)
		}
	})
	b.Run("IsEmptyComparable(0)", func(b *testing.B) {
		for n := 0; n < b.N; n++ {
			_ = IsEmptyComparable(0)
		}
	})

	b.Run("IsEmptyReflect(42)", func(b *testing.B) {
		for n := 0; n < b.N; n++ {
			_ = IsEmptyReflect(42)
		}
	})
	b.Run("IsEmptyReflect(0)", func(b *testing.B) {
		for n := 0; n < b.N; n++ {
			_ = IsEmptyReflect(0)
		}
	})

	b.Run("IsEmptyReflect(map[string]int{'foo': 42})", func(b *testing.B) {
		for n := 0; n < b.N; n++ {
			_ = IsEmptyReflect(map[string]int{"foo": 42})
		}
	})
	b.Run("IsEmptyReflect(map[string]int{})", func(b *testing.B) {
		for n := 0; n < b.N; n++ {
			_ = IsEmptyReflect(map[string]int{})
		}
	})
}

BenchmarkMap/IsEmptyComparable(42)-10           1000000000               0.3126 ns/op          0 B/op          0 allocs/op
BenchmarkMap/IsEmptyComparable(0)-10            1000000000               0.3143 ns/op          0 B/op          0 allocs/op
BenchmarkMap/IsEmptyReflect(42)-10              273421233                4.374 ns/op           0 B/op          0 allocs/op
BenchmarkMap/IsEmptyReflect(0)-10               274970337                4.491 ns/op           0 B/op          0 allocs/op
BenchmarkMap/IsEmptyReflect(map[string]int{'foo':_42})-10               63943872                18.33 ns/op            0 B/op          0 allocs/op
BenchmarkMap/IsEmptyReflect(map[string]int{})-10                        88390464                13.54 ns/op            0 B/op          0 allocs/op