Improve utils of slices (#22379)

- Move the file `compare.go` and `slice.go` to `slice.go`.
- Fix `ExistsInSlice`, it's buggy
  - It uses `sort.Search`, so it assumes that the input slice is sorted.
- It passes `func(i int) bool { return slice[i] == target })` to
`sort.Search`, that's incorrect, check the doc of `sort.Search`.
- Conbine `IsInt64InSlice(int64, []int64)` and `ExistsInSlice(string,
[]string)` to `SliceContains[T]([]T, T)`.
- Conbine `IsSliceInt64Eq([]int64, []int64)` and `IsEqualSlice([]string,
[]string)` to `SliceSortedEqual[T]([]T, T)`.
- Add `SliceEqual[T]([]T, T)` as a distinction from
`SliceSortedEqual[T]([]T, T)`.
- Redesign `RemoveIDFromList([]int64, int64) ([]int64, bool)` to
`SliceRemoveAll[T]([]T, T) []T`.
- Add `SliceContainsFunc[T]([]T, func(T) bool)` and
`SliceRemoveAllFunc[T]([]T, func(T) bool)` for general use.
- Add comments to explain why not `golang.org/x/exp/slices`.
- Add unit tests.

models/auth/oauth2.go

@@ -69,13 +69,13 @@ func (app *OAuth2Application) ContainsRedirectURI(redirectURI string) bool {
 			if ip != nil && ip.IsLoopback() {
 				// strip port
 				uri.Host = uri.Hostname()
-				if util.IsStringInSlice(uri.String(), app.RedirectURIs, true) {
+				if util.SliceContainsString(app.RedirectURIs, uri.String(), true) {
 					return true
 				}
 			}
 		}
 	}
-	return util.IsStringInSlice(redirectURI, app.RedirectURIs, true)
+	return util.SliceContainsString(app.RedirectURIs, redirectURI, true)
 }
 
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