Refactor setting.Other and remove unused SHOW_FOOTER_BRANDING (#24270)

The `SHOW_FOOTER_BRANDING` came from year 2015, and it seems nobody ever
uses it. It only shows an GitHub icon which seems unrelated to Gitea, it
doesn't do what document says. So, remove it.

## ⚠️ Breaking

Users can now remove the key `[other].SHOW_FOOTER_BRANDING` from their
app.ini.

modules/context/context.go

@@ -741,8 +741,7 @@ func Contexter(ctx context.Context) func(next http.Handler) http.Handler {
 
 			ctx.Data["ShowRegistrationButton"] = setting.Service.ShowRegistrationButton
 			ctx.Data["ShowMilestonesDashboardPage"] = setting.Service.ShowMilestonesDashboardPage
-			ctx.Data["ShowFooterBranding"] = setting.ShowFooterBranding
-			ctx.Data["ShowFooterVersion"] = setting.ShowFooterVersion
+			ctx.Data["ShowFooterVersion"] = setting.Other.ShowFooterVersion
 
 			ctx.Data["EnableSwagger"] = setting.API.EnableSwagger
 			ctx.Data["EnableOpenIDSignIn"] = setting.Service.EnableOpenIDSignIn

modules/context/repo.go

@@ -452,7 +452,7 @@ func RepoAssignment(ctx *Context) (cancel context.CancelFunc) {
 	userName := ctx.Params(":username")
 	repoName := ctx.Params(":reponame")
 	repoName = strings.TrimSuffix(repoName, ".git")
-	if setting.EnableFeed {
+	if setting.Other.EnableFeed {
 		repoName = strings.TrimSuffix(repoName, ".rss")
 		repoName = strings.TrimSuffix(repoName, ".atom")
 	}
@@ -540,7 +540,7 @@ func RepoAssignment(ctx *Context) (cancel context.CancelFunc) {
 	ctx.Data["RepoLink"] = ctx.Repo.RepoLink
 	ctx.Data["RepoRelPath"] = ctx.Repo.Owner.Name + "/" + ctx.Repo.Repository.Name
 
-	if setting.EnableFeed {
+	if setting.Other.EnableFeed {
 		ctx.Data["EnableFeed"] = true
 		ctx.Data["FeedURL"] = ctx.Repo.RepoLink
 	}