DYN-9388 Make PythonNet3 default python engine in Dynamo 4.0

[ivaylo-matov]

Purpose

Now superseded by #16548

PR in response to DYN-9388.

• new project to replace DSCPython
• replaced .dll directly from PythonNe3Engine package
• all rewired so Dynamo points at PythonNet3 as default
• when users open old graph with CPython nodes, they get updated to PythonNet3 and toast is displayed. On save another text box appears to explain the changes.

Declarations

Check these if you believe they are true

• Is documented according to the standards
• The level of testing this PR includes is appropriate
• Changes to the API follow Semantic Versioning and are documented in the API Changes document.

Release Notes

Make PythonNet3 default python engine in Dynamo 4.0

Reviewers

@zeusongit
@DynamoDS/eidos

FYIs

@dnenov
@achintyabhat

[github-actions]

See the ticket for this pull request: https://jira.autodesk.com/browse/DYN-9388

[Copilot]

Pull Request Overview

This pull request makes PythonNet3 the default Python engine in Dynamo 4.0, replacing CPython3. This is a major infrastructure change that affects the Python execution environment throughout the application.

Key changes include:

• Replaced the DSCPython library with DSPythonNet3 as the default Python engine
• Added automatic migration functionality to convert CPython3 nodes to PythonNet3 when opening older graphs
• Implemented user notification systems including toast messages and dialog boxes to inform users about the engine change

Reviewed Changes

Copilot reviewed 128 out of 138 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/settings/DynamoSettings-NewSettings.xml	Added setting to hide CPython3 notifications
Multiple test .dyn files	Updated Python nodes from "CPython3" to "PythonNet3" engine
Multiple test .cs files	Updated library references and engine names from DSCPython to DSPythonNet3
src/Libraries/DSPythonNet3/*	New Python engine implementation replacing DSCPython
src/Libraries/DSCPython/*	Old Python engine files being removed/replaced
src/Libraries/PythonNodeModels/*	Updated default engine and localization resources
src/PythonMigrationViewExtension/*	Enhanced migration logic to handle CPython3 to PythonNet3 conversion
src/DynamoCoreWpf/*	Added UI components for notifications and preferences

Files not reviewed (4)

• src/DynamoCoreWpf/Properties/Resources.Designer.cs: Language not supported
• src/Libraries/DSCPython/Properties/Resources.Designer.cs: Language not supported
• src/Libraries/PythonNodeModels/Properties/Resources.Designer.cs: Language not supported
• src/PythonMigrationViewExtension/Properties/Resources.Designer.cs: Language not supported

Comments suppressed due to low confidence (9)