Fix various documentation, user-facing, and source comment typos (#16367)

* Fix various doc, user-facing, and source comment typos

Found via `codespell -q 3 -S ./options/locale,./vendor -L ba,pullrequest,pullrequests,readby`

services/auth/sspi_windows.go

@@ -73,7 +73,7 @@ func (s *SSPI) Free() error {
 }
 
 // Verify uses SSPI (Windows implementation of SPNEGO) to authenticate the request.
-// If authentication is successful, returs the corresponding user object.
+// If authentication is successful, returns the corresponding user object.
 // If negotiation should continue or authentication fails, immediately returns a 401 HTTP
 // response code, as required by the SPNEGO protocol.
 func (s *SSPI) Verify(req *http.Request, w http.ResponseWriter, store DataStore, sess SessionStore) *models.User {

services/issue/assignee.go

@@ -25,7 +25,7 @@ func DeleteNotPassedAssignee(issue *models.Issue, doer *models.User, assignees [
 		}
 
 		if !found {
-			// This function also does comments and hooks, which is why we call it seperatly instead of directly removing the assignees here
+			// This function also does comments and hooks, which is why we call it separately instead of directly removing the assignees here
 			if _, _, err := ToggleAssignee(issue, doer, assignee.ID); err != nil {
 				return err
 			}

services/mailer/mailer.go

@@ -304,7 +304,7 @@ var Sender gomail.Sender
 // NewContext start mail queue service
 func NewContext() {
 	// Need to check if mailQueue is nil because in during reinstall (user had installed
-	// before but swithed install lock off), this function will be called again
+	// before but switched install lock off), this function will be called again
 	// while mail queue is already processing tasks, and produces a race condition.
 	if setting.MailService == nil || mailQueue != nil {
 		return

services/wiki/wiki_test.go

@@ -140,7 +140,7 @@ func TestRepository_AddWikiPage(t *testing.T) {
 			wikiPath := NameToFilename(wikiName)
 			entry, err := masterTree.GetTreeEntryByPath(wikiPath)
 			assert.NoError(t, err)
-			assert.Equal(t, wikiPath, entry.Name(), "%s not addded correctly", wikiName)
+			assert.Equal(t, wikiPath, entry.Name(), "%s not added correctly", wikiName)
 		})
 	}