OLS-3632: Add oc-ols CLI scaffolding and kubeconfig integration - #1936

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@cli/kubeconfig_test.go`:
- Around line 17-176: Convert the tests in cli/kubeconfig_test.go, including
writeTestKubeconfig and all TestLoadKubeConfig_* cases, from testing.T
assertions to the repository’s established Ginkgo/Gomega BDD structure and
matchers. Preserve each test’s existing coverage and expectations, then run make
test to validate the conversion.

In `@cli/kubeconfig.go`:
- Line 34: Update the error-wrapping paths in the kubeconfig loading flow to
define or reuse appropriate error constants and use each constant as the
fmt.Errorf prefix in the “%s: %w” format. Replace the literal prefixes at the
error sites corresponding to lines 34, 44, 51, and 100 while preserving the
existing wrapped errors and behavior.
- Around line 49-53: Trim whitespace from the contents read in the
BearerTokenFile branch before assigning the result to token, matching client-go
behavior. Add or update the token-file test to write the token followed by a
newline and verify the configured token excludes that newline.
- Around line 64-66: Update the tlsConfig initialization in the kubeconfig TLS
setup to assign ServerName from restConfig.TLSClientConfig.ServerName,
preserving kubeconfig tls-server-name overrides for SNI and certificate
validation. Add a regression test covering propagation of this override.

In `@cli/root.go`:
- Around line 13-26: Update NewRootCmd when constructing the root Cobra command
to bind its input, output, and error streams via SetIn, SetOut, and SetErr using
the injected IOStreams, ensuring help and error output use those streams instead
of process-level defaults.

In `@cli/version_test.go`:
- Around line 8-34: Convert the tests in cli/version_test.go (lines 8-34) and
cli/root_test.go (lines 9-60) from testing.T to the required Ginkgo Describe/It
structure with Gomega assertions, reusing an existing CLI suite or adding one
suite entrypoint as needed. Preserve the current version and root-command
behavior checks, including injected Version validation, and verify the changes
with make test.

In `@cli/version.go`:
- Around line 19-20: Wrap both command output write failures with dedicated
error constants: update cli/version.go lines 19-20 around the version-output
write to return fmt.Errorf with its new constant and the original error, and
update cli/root.go lines 21-22 around the default-mode error-output write
similarly with a separate constant; preserve successful output behavior.

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@cli/kubeconfig_test.go`:
- Around line 46-64: Update the negative-path tests using testKubeconfigNoToken
and the nonexistent-file case to assert the specific expected errors:
ErrNoBearerToken for the missing-token scenario and ErrLoadKubeConfig for the
missing-file scenario. Remove the invalid certificate fields from
testKubeconfigNoToken unless the test is intended to cover certificate-only
rejection; if so, replace them with valid certificate and private-key data.
Avoid broad HaveOccurred assertions that could accept unrelated parsing or
context-resolution failures.

In `@cli/kubeconfig.go`:
- Around line 74-79: Update the TLS configuration in LoadKubeConfig so
InsecureSkipVerify incorporates the kubeconfig-derived restConfig.Insecure or
TLSClientConfig.InsecureSkipTLSVerify value, rather than using only the
insecureSkipTLS CLI flag. Preserve the intended CLI-versus-kubeconfig precedence
and update the relevant tests to establish that behavior.
- Line 35: Update the kubeconfig loading setup around loadingRules to use
clientcmd.NewDefaultClientConfigLoadingRules() when kubeconfigPath is empty,
preserving default and KUBECONFIG-based precedence; set ExplicitPath only when a
non-empty override is supplied. Add a regression test covering an empty path
with KUBECONFIG set and verify the configured kubeconfig is loaded.

---

Nitpick comments:
In `@cli/kubeconfig.go`:
- Around line 31-34: Update the applicable AGENTS.md guidance for the
LoadKubeConfig CLI boundary if these rules are not already documented: specify
kubeconfig defaults, token-only authentication, TLS versus CA certificate
precedence, and the required test workflow. Keep the guidance scoped to this
package’s conventions and current behavior.