test: add test coverage for missing permissions

[nan-yu]

There are multiple issues with missing permission, though they all share the same KNV2004 error code. This commit adds test coverage for the following scenarios:

1. A GSA doesn't exist when using gcpserviceaccount
2. A GSA exists, but it is not impersonated with a KSA.
3. A GSA exists and is impersonated, but it doesn't have reader permission.
4. A WI+KSA doesn't have reader permission.

[google-oss-prow[bot]]

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[nan-yu]

I accidentally pushed from the wrong fork branch. I'll push a new patch after addressing these comments.

[google-oss-prow[bot]]

@nan-yu: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
kpt-config-sync-presubmit-e2e-multi-repo-test-group1	c900b866692aa1f7b39a19d1e55c9e4aa44a1000	link	true	/test kpt-config-sync-presubmit-e2e-multi-repo-test-group1
kpt-config-sync-presubmit-e2e-multi-repo-test-group2	c900b866692aa1f7b39a19d1e55c9e4aa44a1000	link	true	/test kpt-config-sync-presubmit-e2e-multi-repo-test-group2
kpt-config-sync-presubmit-e2e-multi-repo-test-group3	c900b866692aa1f7b39a19d1e55c9e4aa44a1000	link	true	/test kpt-config-sync-presubmit-e2e-multi-repo-test-group3
kpt-config-sync-presubmit	c900b866692aa1f7b39a19d1e55c9e4aa44a1000	link	true	/test kpt-config-sync-presubmit
kpt-config-sync-terraform-presubmit	c900b866692aa1f7b39a19d1e55c9e4aa44a1000	link	true	/test kpt-config-sync-terraform-presubmit

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