feat: capture cli logs in tests (#10669)

Adds a Logger to cli Invocation and standardizes CLI commands to use it.  clitest creates a test logger by default so that CLI command logs are captured in the test logs.

CLI commands that do their own log configuration are modified to add sinks to the existing logger, rather than create a new one.  This ensures we still capture logs in CLI tests.

cli/server_createadminuser.go

@@ -42,7 +42,7 @@ func (r *RootCmd) newCreateAdminUserCommand() *clibase.Cmd {
 			}
 
 			cfg := r.createConfig()
-			logger := slog.Make(sloghuman.Sink(inv.Stderr))
+			logger := inv.Logger.AppendSinks(sloghuman.Sink(inv.Stderr))
 			if r.verbose {
 				logger = logger.Leveled(slog.LevelDebug)
 			}