tree(ds): Creating a new member with a conflicting name may cause data-loss

[zFernand0]

Describe the bug

Say that your HLQ.TEST.PDS contains a member called TEST. if you create a new member, and provide the name TEST, the data on your old member will be lost

To Reproduce

1. Create a PDS (HLQ.TEST.PDS)
2. Create a member called TEST
3. Add some content and save the member
4. Now, right click the PDS, and select "Create new member"
5. Name it TEST
6. Notice the conclict error:

And now your contents from step 3 are gone on the mainframe

Expected behavior

Screenshots

Desktop (please complete the following information):

• OS: MacOS
• Zowe Explorer Version: 3.0.2

Additional context

This was discovered by @pujal0909 (Thank you! 🙏 ) when researching:

• Give users the ability to create a copy of a pds zowe-cli#2349

[github-actions]

Thank you for creating a bug report.
We will investigate the bug and evaluate its impact on the product.
If you haven't already, please ensure you have provided steps to reproduce the bug and as much context as possible.

[traeok]

This will need backported to v2 - in both major versions, we allow users to create a new member with the same name even if the member already exists.

The issue exists due to calling Upload.bufferToDataSet with an existing member for the createDataSetMember API - since the member already exists, its contents are replaced with an empty buffer. Ideally, we can add validation from the Zowe Explorer side to make sure the member doesn't exist before calling the API.