Support performance trace (#32973)

1. Add a OpenTelemetry-like shim-layer to collect traces
2. Add a simple builtin trace collector and exporter, end users could
download the diagnosis report to get the traces.

This PR's design is quite lightweight, no hard-dependency, and it is
easy to improve or remove. We can try it on gitea.com first to see
whether it works well, and fine tune the details.

---------

Co-authored-by: silverwind <me@silverwind.io>

routers/web/admin/stacktrace.go

@@ -12,10 +12,17 @@ import (
 	"code.gitea.io/gitea/services/context"
 )
 
+func monitorTraceCommon(ctx *context.Context) {
+	ctx.Data["Title"] = ctx.Tr("admin.monitor")
+	ctx.Data["PageIsAdminMonitorTrace"] = true
+	// Hide the performance trace tab in production, because it shows a lot of SQLs and is not that useful for end users.
+	// To avoid confusing end users, do not let them know this tab. End users should "download diagnosis report" instead.
+	ctx.Data["ShowAdminPerformanceTraceTab"] = !setting.IsProd
+}
+
 // Stacktrace show admin monitor goroutines page
 func Stacktrace(ctx *context.Context) {
-	ctx.Data["Title"] = ctx.Tr("admin.monitor")
-	ctx.Data["PageIsAdminMonitorStacktrace"] = true
+	monitorTraceCommon(ctx)
 
 	ctx.Data["GoroutineCount"] = runtime.NumGoroutine()