[Shipping Labels] Update shipment endpoint - Networking layer

[selanthiraiyan]

Part of: #15308

Description

Adds support for updating shipments in the networking layer.

Changes

• New method in WooShippingRemote to support updating shipments.
• Model files to send shipments and parse response.
• Mapper and mock json files.
• Unit tests.

Steps to reproduce

This endpoint isn't used yet. Unit tests should pass.

Testing information

NA

Screenshots

NA

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• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

Reviewer (or Author, in the case of optional code reviews):

Please make sure these conditions are met before approving the PR, or request changes if the PR needs improvement:

• The PR is small and has a clear, single focus, or a valid explanation is provided in the description. If needed, please request to split it into smaller PRs.
• Ensure Adequate Unit Test Coverage: The changes are reasonably covered by unit tests or an explanation is provided in the PR description.
• Manual Testing: The author listed all the tests they ran, including smoke tests when needed (e.g., for refactorings). The reviewer confirmed that the PR works as expected on all devices (phone/tablet) and no regressions are added.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce iOS Prototype by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce iOS Prototype
	Build Number	29024
	Version	PR #15445
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	42fa5d3
	Installation URL	5g20daj8ug7g0

Automatticians: You can use our internal self-serve MC tool to give yourself access to those builds if needed.

[itsmeichigo]

LGTM