Allows picking showing and hiding measurement units in reports

[AmadeusW]

Introduces ISummaryStyle which can be added to the IConfig and to participating exporters (currently CsvExporter).

The style controls whether units appear in headers, whether they appear in the data and what are the units. If user did not specify units in the style, SummaryTable will set recommended units based on report results.

Participating implementations of IColumn (currently StatisticColumn and two AllocationColumn) render their headers and values based on ISummaryStyle

Closes #146 - Ability to specify units / easier comparison
Closes #118 - Raw data in CSV exports
Resolves a TODO in Windows.MemoryDiagnoser

This PR is a squashed version of #396

[dnfclas]

@AmadeusW,
Thanks for having already signed the Contribution License Agreement. Your agreement was validated by .NET Foundation. We will now review your pull request.
Thanks,
.NET Foundation Pull Request Bot

[AndreyAkinshin]

@AmadeusW. you shouldn't create another PR for the squashed version. It's better to squash the summaryStyle branch and run git push -f; #396 will be automatically updated. It's better because it allows keeping the PR source code and the discussion in the same place. By the way, GitHub allows squashing on merge which is also a great feature.
It seems that we have some confilct in the ManualConfig file (probably because of recent @adamsitnik fixes). Could you resolve it?

[AmadeusW]

Ok I'll go to #396, fix the conflict and you should be able to squash-merge, right?