Add PackagePaths as Parameter of ExecutionSession

[mjkkirschner]

Purpose

Try to address DynamoDS/DynamoWishlist#71

• add parameter key for packagePaths
• add parameter
• add test
• add python test asserting we can reference and use this parameter.

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.

[mjkkirschner]

all tests pass on self serve, but parallel has a concurrency issue with file deletion - will take a look.

[mjkkirschner]

I ran the parallel self serve again and all passed - so I think this is good to review now:
https://master-5.jenkins.autodesk.com/job/Dynamo/job/DynamoSelfServe/job/pullRequestValidation/837

[aparajit-pratap]

I think we should make this class static as well.

[mjkkirschner]

I agree, but I think that would sadly break the API. Do you prefer I obsolete this class, create a static version and use that one?

[mjkkirschner]

or just risk the change?

[aparajit-pratap]

Can we add a TODO to add it later?

[mjkkirschner]

yep, will do.

[mjkkirschner]

added and task created.