build: modernize Go usage

This commit modernizes Go usage. This was done with:

go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@latest -fix -test ./...

Then files needed to be `go fmt`ed and a few comments needed to be
restored.

The modernizations include replacing

- if/else conditional assignment by a call to the built-in min or max functions added in go1.21
- sort.Slice(x, func(i, j int) bool) { return s[i] < s[j] } by a call to slices.Sort(s), added in go1.21
- interface{} by the 'any' type added in go1.18
- append([]T(nil), s...) by slices.Clone(s) or slices.Concat(s), added in go1.21
- loop around an m[k]=v map update by a call to one of the Collect, Copy, Clone, or Insert functions from the maps package, added in go1.21
- []byte(fmt.Sprintf...) by fmt.Appendf(nil, ...), added in go1.19
- append(s[:i], s[i+1]...) by slices.Delete(s, i, i+1), added in go1.21
- a 3-clause for i := 0; i < n; i++ {} loop by for i := range n {}, added in go1.22

fs/operations/operations.go

@@ -593,7 +593,7 @@ func DeleteFilesWithBackupDir(ctx context.Context, toBeDeleted fs.ObjectsChan, b
 	var errorCount atomic.Int32
 	var fatalErrorCount atomic.Int32
 
-	for i := 0; i < ci.Checkers; i++ {
+	for range ci.Checkers {
 		go func() {
 			defer wg.Done()
 			for dst := range toBeDeleted {
@@ -732,7 +732,7 @@ func SameDir(fdst, fsrc fs.Info) bool {
 }
 
 // Retry runs fn up to maxTries times if it returns a retriable error
-func Retry(ctx context.Context, o interface{}, maxTries int, fn func() error) (err error) {
+func Retry(ctx context.Context, o any, maxTries int, fn func() error) (err error) {
 	for tries := 1; tries <= maxTries; tries++ {
 		// Call the function which might error
 		err = fn()
@@ -777,7 +777,7 @@ var StdoutMutex sync.Mutex
 // This writes to stdout holding the StdoutMutex. If you are going to
 // override it and write to os.Stdout then you should hold the
 // StdoutMutex too.
-var SyncPrintf = func(format string, a ...interface{}) {
+var SyncPrintf = func(format string, a ...any) {
 	StdoutMutex.Lock()
 	defer StdoutMutex.Unlock()
 	fmt.Printf(format, a...)
@@ -788,7 +788,7 @@ var SyncPrintf = func(format string, a ...interface{}) {
 // Ignores errors from Fprintf.
 //
 // Prints to stdout if w is nil
-func SyncFprintf(w io.Writer, format string, a ...interface{}) {
+func SyncFprintf(w io.Writer, format string, a ...any) {
 	if w == nil || w == os.Stdout {
 		SyncPrintf(format, a...)
 	} else {
@@ -2443,7 +2443,7 @@ func DirMove(ctx context.Context, f fs.Fs, srcRemote, dstRemote string) (err err
 	}
 	renames := make(chan rename, ci.Checkers)
 	g, gCtx := errgroup.WithContext(context.Background())
-	for i := 0; i < ci.Checkers; i++ {
+	for range ci.Checkers {
 		g.Go(func() error {
 			for job := range renames {
 				dstOverwritten, _ := f.NewObject(gCtx, job.newPath)
@@ -2551,7 +2551,7 @@ var (
 // skipDestructiveChoose asks the user which action to take
 //
 // Call with interactiveMu held
-func skipDestructiveChoose(ctx context.Context, subject interface{}, action string) (skip bool) {
+func skipDestructiveChoose(ctx context.Context, subject any, action string) (skip bool) {
 	// Lock the StdoutMutex - must not call fs.Log anything
 	// otherwise it will deadlock with --interactive --progress
 	StdoutMutex.Lock()
@@ -2601,7 +2601,7 @@ func skipDestructiveChoose(ctx context.Context, subject interface{}, action stri
 //
 // Together they should make sense in this sentence: "Rclone is about
 // to action subject".
-func SkipDestructive(ctx context.Context, subject interface{}, action string) (skip bool) {
+func SkipDestructive(ctx context.Context, subject any, action string) (skip bool) {
 	var flag string
 	ci := fs.GetConfig(ctx)
 	switch {