Fix: product connection sorting

[kidunot89]

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What does this implement/fix? Explain your changes.

• Fixes reverse pagination when sorting by pricing fields
• Fixes sorting for non-root product queries.

Does this close any currently open issues?

Resolves #513
Resolves #506

Any relevant logs, error output, GraphiQL screenshots, etc?

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Any other comments?

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Where has this been tested?

• WooGraphQL Version: 0.10.0
• WPGraphQL Version: 1.5.0
• WordPress Version:
• WooCommerce Version: