Fix privilege issue

[mssun]

Description

Fix privilege issues.

• fix inconsistency of GetFunction and ListFunctions interfaces
• add GetKeysByPrefix interface to the storage service to help the fix

Fixes #624

Type of change (select or add applied and delete the others)

• Bug fix (non-breaking change which fixes an issue)
• New interface

How has this been tested?

• CI test: https://ci.mesalock-linux.org/mssun/incubator-teaclave/159
• new test cases

Checklist

• Fork the repo and create your branch from master.
• If you've added code that should be tested, add tests.
• If you've changed APIs, update the documentation.
• Ensure the tests pass (see CI results).
• Make sure your code lints/format.

[AI-Memory]

LGTM +1, thanks.