Add ability to set multiple redirect URIs in OAuth application UI (#25072)

OAuth applications can already have multiple redirect URIs if
created/edited over API.

This change allows for setting multiple redirect URIs through the UI as
a comma-separated list (e. g.
`https://example.org/redirect,https://redirect.example.org`)

<details>
<summary>Screenshots</summary>

![Bildschirmfoto vom 2023-06-04
17-14-40](https://github.com/go-gitea/gitea/assets/47871822/2206dc32-e7e4-4953-9ecb-e098890b3f54)
![Bildschirmfoto vom 2023-06-04
17-14-50](https://github.com/go-gitea/gitea/assets/47871822/cd97c73c-9310-44ee-a83a-b927a1ef94da)

</details>

Closes #25068

1 files changed, 18 insertions, 1 deletions

diff --git a/modules/util/truncate.go b/modules/util/truncate.go
index f41d27d8b7..77b116eeff 100644
--- a/modules/util/truncate.go
+++ b/modules/util/truncate.go
@@ -3,7 +3,10 @@
 
 package util
 
-import "unicode/utf8"
+import (
+	"strings"
+	"unicode/utf8"
+)
 
 // in UTF8 "…" is 3 bytes so doesn't really gain us anything...
 const (
@@ -35,3 +38,17 @@ func SplitStringAtByteN(input string, n int) (left, right string) {
 
 	return input[:end] + utf8Ellipsis, utf8Ellipsis + input[end:]
 }
+
+// SplitTrimSpace splits the string at given separator and trims leading and trailing space
+func SplitTrimSpace(input, sep string) []string {
+	// replace CRLF with LF
+	input = strings.ReplaceAll(input, "\r\n", "\n")
+
+	var stringList []string
+	for _, s := range strings.Split(input, sep) {
+		// trim leading and trailing space
+		stringList = append(stringList, strings.TrimSpace(s))
+	}
+
+	return stringList
+}