Multidirectory

[MarkWolters]

This PR expands the capability of the DiskUsageMonitor in the BenchYAML and autoBenchYAML testing applications to be able to monitor more than a single directory and to provide detailed information on disk used and number of new files for each directory monitored, as well as a summary of the total bytes used and number of new files across all monitored directories.

Although this allows DiskUsageMonitor to monitor an arbitrary number of directories in practice as of this PR it is used to monitor the work directory and the cache directory which contains indexes that may be reused for testing purposes.

example rollup summary at index construction time:

Disk Usage Summary Graph Index Build:
  [testDirectory]:
    Total Disk Used: 1.61 GB
    Total Files: 1
    Net Change: 1.61 GB, +1 files
  [indexCache]:
    Total Disk Used: 0 B
    Total Files: 0
    Net Change: 0 B, +0 files
  [Overall Total]:
    Total Disk Used: 1.61 GB
    Total Files: 1
    Net Change: 1.61 GB, +1 files
Index build time: 956.781921 seconds

[github-actions]

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[jshook]

Looks ok.

[tlwillke]

Works as expected. Code changes look good. Looking forward to per-index disk usage in a future PR.

[tlwillke]

LGTM. Reviewed the changes and retested. Working as expected.