Update Initial Directory to Be Based on Last Set File Path

[QilongTang]

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Purpose

Per https://jira.autodesk.com/browse/DYN-4564, updating the initial directory in the file picker dialog to be based on the last set file path on the node, if there is no path set, then defaulting back to system behavior (last picked directory).

After:

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

Release Notes

Update initial directory to be based on last set file path

Reviewers

@DynamoDS/dynamo

FYIs

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[QilongTang]

tests passed on https://master-15.jenkins.autodesk.com/view/DYN/job/DYN-DevCI_Self_Service/1039/