govc: Add support for prompting password from stdin

[eaaltonen]

Description

Add support for the govc tool to prompt for the password directly.

Type of change

Please mark options that are relevant:

• [X] New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Run govc find / -type m with vSphere cluster. Enter password when prompted, and check that the command succeeds and output contains VMs.

• [ ] Test Description 1
• [ ] Test Description 2

Checklist:

• [X] My code follows the CONTRIBUTION guidelines of this project
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] New and existing unit tests pass locally with my changes
• [ ] Any dependent changes have been merged

[vmwclabot]

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[github-actions[bot]]

This Pull Request is stale because it has been open for 90 days with no activity. It will automatically close after 30 more days of inactivity. Mark as fresh by adding the comment /remove-lifecycle stale.