Add mass recovery endpoints

[rish-singhal]

Description

In this PR we add new endpoints for the new feature mass recovery

PS> Start-MassRecovery -Name $name -RecoveryPoint $recoveryPoint -SubscriptionName $subscriptionName -AdGroupId $adGroupId -WorkloadType $workloadType # only "OneDrive" is valid

PS> Get-MassRecoveryProgress -MassRecoveryInstanceId $massRecoveryInstanceId

PS> Stop-MassRecovery -MassRecoveryInstanceId $massRecoveryInstanceId ## NOTE: need to use STOP as CANCEL is not approved verb for naming

Related Issue

Closes #32

Motivation and Context

As we are going to release mass recovery as API only endpoint for beta, we have added support for these in powershell.

How Has This Been Tested?

Have tested out all the cases of failed/succeeded mass recovery as well as get mass recovery progress at various points of time.

Screenshots (if appropriate):

Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

Go over all the following points, and put an x in all the boxes that apply. If you're unsure about any of these, don't hesitate to ask. We're here to help!

• [x] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTION document.
• [ ] I have updated the CHANGELOG file accordingly for the version that this merge modifies.

[rish-singhal]

@drew-russell could you review this PR. Thanks!

[rish-singhal]

@pmilano1 I have updated Start-MassRecovery to take in WorkloadType as an argument which explicitly specifies "OneDrive".