New cmdlets needed to support MSSQL functionality

[clumnah]

We need to add additional functionality via cmdlets to support mssql. Below are APIs needing cmdlets

V1

• /mssql/hierarchy/{id}
• /mssql/hierarchy/{id}/descendants
• /mssql/instance/count
• /mssql/db/bulk
• ​/mssql​/db​/{id}​/missed_snapshot
• /mssql/db/{id}/missed_recoverable_range
• /mssql/db/recoverable_range/download/{id}
• /mssql/db/{id}/compatible_instance
• /mssql/db/bulk/snapshot/{id}
• /mssql/db/{id}/download_files
• /mssql/db/{id}/download_files_by_id
• ​/mssql​/db​/{id}​/restore_estimate
• /mssql/db/{id}/download
• /mssql/db/bulk/snapshot
• /mssql/db/defaults
• /mssql/hierarchy/{id}/children
• /mssql/request/{id}
• /mssql/db/{id}/browse
• /mssql/sla_domain/assign

V2

• ​/mssql​/db​/log_shipping​/{id}​/update
• ​/mssql​/db​/{id}​/log_shipping
• ​/mssql​/db​/log_shipping
• ​/mssql​/db​/log_shipping​/{id}
• ​/mssql​/db​/log_shipping​/{id}
• ​/mssql​/sla_domain​/assign