DYN-6365 Promote Gate node from GD Extension to Dynamo Core.

[saintentropy]

Purpose

The purpose of the PR is to migrate the Gate Node from the GD Extension to Dynamo Core.

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
• This PR contains no files larger than 50 MB

Release Notes

Dynamo now has the Gate node in the Out of the Box Library. The gate node allows you control the execution in sections of you graph. An open Gate passes data through unchanged. A closed Gate sends no data downstream.

Reviewers

@LongNguyenP @twastvedt

FYIs

@jnealb

[twastvedt]

I assume this is just copied from the extension - any changes from that code that require more careful inspection?

Also, can we consider an icon change? The icon looks to me like a circuit switch symbol, where "open" means no electricity flows through. Instead our terminology treats this node more like a fence gate: "open" means the cows flow through. Perhaps we could change the icon to something that reflects this? The description is, admittedly, clear, but I think many people's immediate instinct might be "incorrect" based on the icon.

[QilongTang]

Regressions:
NodeDocumentationMarkdownGeneratorTests.MarkdownGeneratorCommandTests.CanOverWriteExistingFiles
NodeDocumentationMarkdownGeneratorTests.MarkdownGeneratorCommandTests.CanScanAssemblyFromPath
NodeDocumentationMarkdownGeneratorTests.MarkdownGeneratorCommandTests.ProducesCorrectOutputFromDirectory