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/rc_test.go

@@ -530,12 +530,12 @@ func TestRcFsInfo(t *testing.T) {
 	assert.Equal(t, want.Root, got["Root"])
 	assert.Equal(t, want.String, got["String"])
 	assert.Equal(t, float64(want.Precision), got["Precision"])
-	var hashes []interface{}
+	var hashes []any
 	for _, hash := range want.Hashes {
 		hashes = append(hashes, hash)
 	}
 	assert.Equal(t, hashes, got["Hashes"])
-	var features = map[string]interface{}{}
+	var features = map[string]any{}
 	for k, v := range want.Features {
 		features[k] = v
 	}
@@ -627,7 +627,7 @@ func TestRcCommand(t *testing.T) {
 		assert.Contains(t, err.Error(), "command not found")
 		return
 	}
-	want := rc.Params{"result": map[string]interface{}{
+	want := rc.Params{"result": map[string]any{
 		"arg": []string{
 			"path1",
 			"path2",