proposal: Another PickByKeys that ouputs a slice

[MakDon]

Example

m := lo. PickByKeys(map[string]int{"foo": 1, "bar": 2, "baz": 3}, []string{"foo", "baz"})
// []int{1,3}

The output values' order should be the same as the input slice.

Why we need it

Assume we have a list of openids:

openids = []string{openid1, openid2}

Then we have a method to transfer it into user_id:

func ToUserIDs(openids []string) map[string]string{}

The output of ToUserIDs is a map, in which the key is openid and the value is UserID.

If I call Values, then i would get a unordered list, which can not keep the original order with openids

So maybe we need one "Ordered PickByKeys function that returns a slice"?

Further more, the method could support the following scene:

	gourpA := []string{openid1, openid2, openid3}
	gourpB := []string{openid4, openid5, openid6}
	gourpC := []string{openid7, openid8, openid9}
	all := append([]string{}, gourpA...)
	all := append(all, gourpB...)
	all := append(all, gourpC...)
	users := fetchUsers(all)
	usersA := lo.PickByKeys(users, gourpA)
	usersB := lo.PickByKeys(users, gourpB)
	usersC := lo.PickByKeys(users, gourpC)

Join all the IDs, fetch in one request, then separate the returned entities into different groups.