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/chunkedreader/chunkedreader_test.go

@@ -80,10 +80,7 @@ func testRead(content []byte, mode mockobject.SeekMode, streams int) func(*testi
 							require.Equal(t, offset, p, what)
 
 							n, err := cr.Read(buf)
-							end := offset + int64(bl)
-							if end > cl {
-								end = cl
-							}
+							end := min(offset+int64(bl), cl)
 							l := int(end - offset)
 							if l < bl {
 								require.Equal(t, io.EOF, err, what)