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>

modules/git/command_test.go

@@ -58,5 +58,5 @@ func TestCommandString(t *testing.T) {
 	assert.EqualValues(t, cmd.prog+` a "-m msg" "it's a test" "say \"hello\""`, cmd.LogString())
 
 	cmd = NewCommandContextNoGlobals(context.Background(), "url: https://a:b@c/", "/root/dir-a/dir-b")
-	assert.EqualValues(t, cmd.prog+` "url: https://sanitized-credential@c/" dir-a/dir-b`, cmd.LogString())
+	assert.EqualValues(t, cmd.prog+` "url: https://sanitized-credential@c/" .../dir-a/dir-b`, cmd.LogString())
 }