Switch to swagger generated SDK for operational insights powershell commands

[xizha162]

Description

1. Resubmitting the PR for switching to swagger generated .Net SDK client for OperationalInsights powershell commands since we will soon retire Hydra SDK. There are no API behavior change. Mostly syntax change.
2. Added a small change to include retentionInDays parameter for workspace operations.

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[xizha162]

@shahabhijeet Fixed the build error from last week and Haitao also signed off. Could you take a look now? There was minimal functional change. The main change is just switching to operational insight SDK 0.18 which is based on swagger now.

[markcowl]

One minor change and need to pass the on demand run, other wise LGTM

[markcowl]

Please remove the position property from this parameter. > 4 positional parameters is too many.

[xizha162]

@markcowl , fixed by removing the position parameter.

[xizha162]

@markcowl , @shahabhijeet , I addressed the comments. Please take a look and sign off if no other issues. Thank you very much!

[markcowl]

on demand run here: http://azuresdkci.cloudapp.net/view/1-AzurePowerShell/job/powershell-demand/1594/

LGTM once this passes