feat: add cli command scaletest dynamic-parameters (#20034)

part of https://github.com/coder/internal/issues/912

Adds CLI command `coder exp scaletest dynamic-parameters`

I've left out the configuration of tracing and timeouts for now. I think I want to do some refactoring of the scaletest CLI to make handling those flags take up less boiler plate.

I will add tracing and timeout flags in a follow up PR.

cli/exp_scaletest.go

@@ -60,6 +60,7 @@ func (r *RootCmd) scaletestCmd() *serpent.Command {
 		Children: []*serpent.Command{
 			r.scaletestCleanup(),
 			r.scaletestDashboard(),
+			r.scaletestDynamicParameters(),
 			r.scaletestCreateWorkspaces(),
 			r.scaletestWorkspaceUpdates(),
 			r.scaletestWorkspaceTraffic(),