Update icons for new PolyCurve.ByThickeningCurveNormal node

[aparajit-pratap]

Purpose

This PR sets the icon for the old PolyCurve.ByThickeningCurve node on the new one as the old one is deprecated.

Declarations

Check these if you believe they are true

• The codebase is in a better state after this PR
• Is documented according to the standards
• The level of testing this PR includes is appropriate
• User facing strings, if any, are extracted into *.resx files
• All tests pass using the self-service CI.
• Snapshot of UI changes, if any.
• Changes to the API follow Semantic Versioning and are documented in the API Changes document.
• This PR modifies some build requirements and the readme is updated

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FYIs

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[QilongTang]

Test failure: ViewExtensionLibraryTests.DynamoLibraryItemsTests.VerifyIconsForLibraryItems

[QilongTang]

DynamoCoreWpfTests.JSONSerializationTests.NewCustomNodeSaveAndLoadPt2 This test look irrelevant but failing, can you verify locally?

[aparajit-pratap]

@QilongTang the test passes for me locally but it is supposed to run right after NewCustomNodeSaveAndLoadPt1.

[QilongTang]

OK if https://master-15.jenkins.autodesk.com/view/DYN/job/DYN-Dynamo/job/DynamoBuildscripts/job/master/772/ pass, I will merge this after.