cmd/testwrapper: output packages tested

Previously it would only print the failures without providing
more information on which package the failures from.

This commit makes it so that it prints out the package information
as well as the attempt numbers.

```
➜  tailscale.com git:(main) ✗ go run ./cmd/testwrapper ./cmd/...
ok       tailscale.com/cmd/derper
ok       tailscale.com/cmd/k8s-operator
ok       tailscale.com/cmd/tailscale/cli
ok       tailscale.com/cmd/tailscaled
=== RUN   TestFlakeRun
    flakytest.go:38: flakytest: issue tracking this flaky test: https://github.com/tailscale/tailscale/issues/0
    flakytest_test.go:41: First run in testwrapper, failing so that test is retried. This is expected.
--- FAIL: TestFlakeRun (0.00s)
FAIL     tailscale.com/cmd/testwrapper/flakytest

Attempt #2: Retrying flaky tests:

ok       tailscale.com/cmd/testwrapper/flakytest
```

Updates #8493

Signed-off-by: Maisem Ali <maisem@tailscale.com>

cmd/testwrapper/testwrapper.go

@@ -23,6 +23,7 @@ import (
 	"time"
 
 	"golang.org/x/exp/maps"
+	"golang.org/x/exp/slices"
 	"tailscale.com/cmd/testwrapper/flakytest"
 )
 
@@ -174,58 +175,96 @@ func main() {
 	}
 	pattern, otherArgs := args[0], args[1:]
 
-	toRun := []*packageTests{ // packages still to test
-		{pattern: pattern},
+	type nextRun struct {
+		tests   []*packageTests
+		attempt int
 	}
 
-	pkgAttempts := make(map[string]int) // tracks how many times we've tried a package
+	toRun := []*nextRun{
+		{
+			tests:   []*packageTests{{pattern: pattern}},
+			attempt: 1,
+		},
+	}
+
+	printPkgStatus := func(pkgName string, failed bool) {
+		if failed {
+			fmt.Println("FAIL\t", pkgName)
+		} else {
+			fmt.Println("ok\t", pkgName)
+		}
+	}
 
-	attempt := 0
 	for len(toRun) > 0 {
-		attempt++
-		var pt *packageTests
-		pt, toRun = toRun[0], toRun[1:]
+		var thisRun *nextRun
+		thisRun, toRun = toRun[0], toRun[1:]
 
-		toRetry := make(map[string][]string) // pkg -> tests to retry
+		if thisRun.attempt >= maxAttempts {
+			fmt.Println("max attempts reached")
+			os.Exit(1)
+		}
+		if thisRun.attempt > 1 {
+			fmt.Printf("\n\nAttempt #%d: Retrying flaky tests:\n\n", thisRun.attempt)
+		}
 
 		failed := false
-		for _, tr := range runTests(ctx, attempt, pt, otherArgs) {
-			if *v || tr.outcome == "fail" {
-				io.Copy(os.Stderr, &tr.logs)
-			}
-			if tr.outcome != "fail" {
-				continue
-			}
-			if tr.isMarkedFlaky {
-				toRetry[tr.name.pkg] = append(toRetry[tr.name.pkg], tr.name.name)
-			} else {
-				failed = true
+		toRetry := make(map[string][]string) // pkg -> tests to retry
+		for _, pt := range thisRun.tests {
+			output := runTests(ctx, thisRun.attempt, pt, otherArgs)
+			slices.SortFunc(output, func(i, j *testAttempt) bool {
+				if c := strings.Compare(i.name.pkg, j.name.pkg); c < 0 {
+					return true
+				} else if c > 0 {
+					return false
+				}
+				return strings.Compare(i.name.name, j.name.name) <= 0
+			})
+
+			lastPkg := ""
+			lastPkgFailed := false
+			for _, tr := range output {
+				if lastPkg == "" {
+					lastPkg = tr.name.pkg
+				} else if lastPkg != tr.name.pkg {
+					printPkgStatus(lastPkg, lastPkgFailed)
+					lastPkg = tr.name.pkg
+					lastPkgFailed = false
+				}
+				if *v || tr.outcome == "fail" {
+					io.Copy(os.Stdout, &tr.logs)
+				}
+				if tr.outcome != "fail" {
+					continue
+				}
+				lastPkgFailed = true
+				if tr.isMarkedFlaky {
+					toRetry[tr.name.pkg] = append(toRetry[tr.name.pkg], tr.name.name)
+				} else {
+					failed = true
+				}
 			}
+			printPkgStatus(lastPkg, lastPkgFailed)
 		}
 		if failed {
+			fmt.Println("\n\nNot retrying flaky tests because non-flaky tests failed.")
 			os.Exit(1)
 		}
+		if len(toRetry) == 0 {
+			continue
+		}
 		pkgs := maps.Keys(toRetry)
 		sort.Strings(pkgs)
+		nextRun := &nextRun{
+			attempt: thisRun.attempt + 1,
+		}
 		for _, pkg := range pkgs {
 			tests := toRetry[pkg]
 			sort.Strings(tests)
-			pkgAttempts[pkg]++
-			if pkgAttempts[pkg] >= maxAttempts {
-				fmt.Println("Too many attempts for flaky tests:", pkg, tests)
-				continue
-			}
-			fmt.Println("\nRetrying flaky tests:", pkg, tests)
-			toRun = append(toRun, &packageTests{
+			nextRun.tests = append(nextRun.tests, &packageTests{
 				pattern: pkg,
 				tests:   tests,
 			})
 		}
+		toRun = append(toRun, nextRun)
 	}
-	for _, a := range pkgAttempts {
-		if a >= maxAttempts {
-			os.Exit(1)
-		}
-	}
-	fmt.Println("PASS")
 }