Multiple clicks on Datasets/Dataset Members can display empty file if network latency sufficient

[awharn]

Describe the bug

When a dataset or dataset member is double (or more) clicked in Zowe Explorer, it is possible for an empty file to be displayed to the user while the contents are being downloaded. This can result in language servers misidentifying the file type, or allow the user to start typing and cause a file contents conflict.

To Reproduce

Steps to reproduce the behavior:

1. Have a slow network connection, or artificially slow down your network connection (i.e. with HAProxy tcp-request inspect-delay)
2. Click a dataset or dataset member more then once
3. Watch empty file be displayed with Plain Text language applied
4. Watch file contents populate after a few moments

Expected behavior

The file should not open until all of the contents are downloaded from the mainframe and populated in the document.

Screenshots

Desktop (please complete the following information):

• OS: Windows 10
• Zowe Explorer Version: 2.9.2
• (Optional) Zowe CLI Version: N/A
• (Optional) Are you using Secure Credential Store? N/A

Additional context

Does not apply to Jobs or USS Files

[github-actions]

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