feat: add In function

[thedevsaddam]

Introduce In function for element existence check in a collection

Checks if an element exists in the collection. It returns true if the element is found; otherwise, false.

result := lo.In([]int{1, 2, 3, 4, 5}, 4)
// true

result = lo.In([]string{"a", "b"}, "c")
// false

Note: This can be done using existing lo.Count([]int{1, 5, 1}, 1)>0 or using lo.CountBy

The In function offers several advantages:

• Readability and Intent: The In function explicitly states its purpose of checking for element existence, making the code easier to understand.
• Performance: TheIn function returns immediately upon finding the first match, while the Count function iterates through the entire collection even if it finds a match early. This can lead to unnecessary iterations, especially in large collections
• Return Value: The In function returns a boolean, which is a straightforward answer to the question of whether the element exists. In contrast, Count returns a count, which is more information than needed for a simple existence check.

[SnowOnion]

lo contains lo.Contains already. ^_^ lo.Contains :: func[T comparable](collection []T, element T) bool

Since go1.21, stdlib slices is added and it contains Contains, too. slices.Contains :: func[S ~[]E, E comparable](s S, v E) bool

https://godoogle.sonion.xyz/search?q=%5BT+comparable%5Dfunc%28collection+%5B%5DT%2C+needle+T%29+bool

[thedevsaddam]

Thank you for the feedback! Given that similar functionality already exists, I'll go ahead and close this PR. I appreciate the insights!