This PR adds a test that generates a synthentic filelist of a variable size, and then measures the time it takes to recreate the fileset.
As there was a reported slowdown, analysis indicated that the query would grow in the order of O=N^2, where N is the number of paths.
The code is then updated to instead use some temporary on-disk space to lay out the paths and then insert them as a new fileset. This should bring the time down to O=N.
Based on a test with 10k files, the query speed up is ~900x, but will be more on larger filesets.
Kenneth Skovhede
ab487bdde2