Enable gosec/golangci-lint, then fix reported errors

[jgwest]

What type of PR is this?

Uncomment only one /kind line, and delete the rest.
For example, > /kind bug would simply become: /kind bug

/kind cleanup

What does this PR do / why we need it:

• Add gosec and golangci-lint targets to Makefile

• Add call to gosec and golangci-lint (with default settings) to GitHub workflow

• Adds ginkgo-linter, which ensures that Ginkgo code is properly formatted (we used this on managed-gitops project, and it was created by a Red Hatter who reached out to let us know about it, previously)

• The rest of the PR is cleaning up issues identified by gosec and golangci-lint

• You'll occasionally see cases where I've had to 'smother' a line with lint ignores, like so:

	//lint:ignore SA1019 known to be deprecated
	assert.DeepEqual(t, testArgoCD.Spec.Grafana.Resources, testGrafanaResources) //nolint:staticcheck // SA1019: We must test deprecated fields.

• Unfortunately this is necessary to add ignores for BOTH VS Code warnings AND golangci-lint errors

[jgwest]

/retest

[jannfis]

/lgtm

[jannfis]

/approve

[openshift-ci]

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This pull-request has been approved by: jannfis

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[jgwest]

Thanks @jannfis!

Merging, as the Konflux workflow error appears unrelated to this PR:

✕ [Violation] slsa_source_correlated.expected_source_code_reference
  ImageRef: quay.io/redhat-user-workloads/rh-openshift-gitops-tenant/dex@sha256:11a13a97b4450b01934a7632692511d1fef1357af9cdbdfdf29f19854203ac6b
  Reason: The expected source code reference
  "git+https://github.com/rh-gitops-midstream/downstream-dex@149705e191549b57c62b0567a87f99406e96e6ae" is not attested