x/tools/cmd/heapview: rename heapdump to heapview

Updates golang/go#16410

Change-Id: I0133971f9a1149da6d88180fc2e378003f189cc8
Reviewed-on: https://go-review.googlesource.com/25101
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
1 file changed