Upgrade Helix to 2.16.1

[sm6srw]

Purpose

DYN-3769: Dynamo freeze/crash multiple screen or display resolution.

This pull request does:

• upgrade helix to version 2.16.1.
• update two tests to use the new API in 2.16 for accessing textures from the texture cache (textures are not a member of the TextureModel anymore).

Helix 2.16 also have breaking API changes to low level hit methods but these are not directly used by Dynamo.

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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