Avido/feature request multiple shipments

[avido]

Description

Added batch request for multiple shipments.

Motivation and context

To prevent overhead / multiple calls for a batch of shipments, added batch request.
Chosen to add new methods to keep old method in tact.

Ref: #45

How has this been tested?

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

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