fix: grant GetObject permissions in AgcPermissionStack user policy

[patmagee]

Description of Changes

Added GetObject and GetObjectVersion' permissions on the agc project bucket to be granted as part of the AgcPermissionStack. This permissions was omitted in the userpolicy` despite being able to perform most other operations including delete destructive ones.

Description of how you validated changes

I ran the CDK locally and validated that the user assigned the policy: AgcPermissionStack-agcuserpolicy* was able to read objects from the s3 bucket directly.

Checklist

• If this change would make any existing documentation invalid, I have included those updates within this PR
• I have added unit tests that prove my fix is effective or that my feature works
• I have linted my code before raising the PR
• Title of this Pull Request follows Conventional Commits standard: https://www.conventionalcommits.org/en/v1.0.0/

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