Add API endpoint for accessing repo topics (#7963)

* Create API endpoints for repo topics.

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Generate swagger

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Add documentation to functions

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Grammar fix

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Fix function comment

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Can't use FindTopics when looking for a single repo topic, as it doesnt use exact match

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Add PUT ​/repos​/{owner}​/{repo}​/topics and remove GET ​/repos​/{owner}​/{repo}​/topics

* Ignore if topic is sent twice in same request, refactoring.

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Fix topic dropdown with api changes.

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Style fix

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Update API documentation

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Better way to handle duplicate topics in slice

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Make response element TopicName an array of strings, instead of using an array of TopicName

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Add test cases for API Repo Topics.

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Fix format of tests

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Fix comments

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Fix unit tests after adding some more topics to the test fixture.

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Update models/topic.go

Limit multiple if else if ...

Co-Authored-By: Antoine GIRARD <sapk@users.noreply.github.com>

* Engine as first parameter in function

Co-Authored-By: Antoine GIRARD <sapk@users.noreply.github.com>

* Replace magic numbers with http status code constants.

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Fix variable scope

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Test one read with login and one with token

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Add some more tests

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Apply suggestions from code review

Use empty struct for efficiency

Co-Authored-By: Lauris BH <lauris@nix.lv>

* Add test case to check access for user with write access

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Fix access, repo admin required to change topics

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Correct first test to be without token

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

* Any repo reader should be able to access topics.

* No need for string pointer

Signed-off-by: David Svantesson <davidsvantesson@gmail.com>

routers/repo/topic.go

@@ -27,24 +27,11 @@ func TopicsPost(ctx *context.Context) {
 		topics = strings.Split(topicsStr, ",")
 	}
 
-	invalidTopics := make([]string, 0)
-	i := 0
-	for _, topic := range topics {
-		topic = strings.TrimSpace(strings.ToLower(topic))
-		// ignore empty string
-		if len(topic) > 0 {
-			topics[i] = topic
-			i++
-		}
-		if !models.ValidateTopic(topic) {
-			invalidTopics = append(invalidTopics, topic)
-		}
-	}
-	topics = topics[:i]
+	validTopics, invalidTopics := models.SanitizeAndValidateTopics(topics)
 
-	if len(topics) > 25 {
+	if len(validTopics) > 25 {
 		ctx.JSON(422, map[string]interface{}{
-			"invalidTopics": topics[:0],
+			"invalidTopics": nil,
 			"message":       ctx.Tr("repo.topic.count_prompt"),
 		})
 		return
@@ -58,7 +45,7 @@ func TopicsPost(ctx *context.Context) {
 		return
 	}
 
-	err := models.SaveTopics(ctx.Repo.Repository.ID, topics...)
+	err := models.SaveTopics(ctx.Repo.Repository.ID, validTopics...)
 	if err != nil {
 		log.Error("SaveTopics failed: %v", err)
 		ctx.JSON(500, map[string]interface{}{