Use AppSubUrl for more redirections (#8647) (#8652)

Partial backport without changes to locale files.

Fix #8461 - fix misspelling of {{AppSubUrl}} and other misspelling in template
Fixes /explore and organisation redirection

routers/home.go

@@ -272,7 +272,7 @@ func ExploreOrganizations(ctx *context.Context) {
 // ExploreCode render explore code page
 func ExploreCode(ctx *context.Context) {
 	if !setting.Indexer.RepoIndexerEnabled {
-		ctx.Redirect("/explore", 302)
+		ctx.Redirect(setting.AppSubURL+"/explore", 302)
 		return
 	}