⚠️Rename ErrorMessage and ErrorReason to FailureMessage and FailureReason

[noamran]

What this PR does / why we need it:
Renames the ErrorMessage and ErrorReason fields to FailureMessage and FailureReason in
GCPMachineStatus.

Which issue(s) this PR fixes :
Fixes #256

[k8s-ci-robot]

Hi @noamran. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[detiber]

/ok-to-test

[vincepri]

@noamran You can ignore the conformance failure for now, need to debug it today

[vincepri]

/test pull-cluster-api-provider-gcp-make-conformance

[noamran]

/test pull-cluster-api-provider-gcp-make-conformance

[vincepri]

/approve
/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: noamran, vincepri

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