Add Protobuf Matcher utility

[AndrewSirenko]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/kind api-change
/kind bug
/kind cleanup
/kind design
/kind documentation
/kind failing-test
/kind feature
/kind flake

/feature

What this PR does / why we need it:

Source: @jsafrane's kubernetes-csi/external-provisioner#1262

gomock is not able to match newly generated Protobuf messages from csi-test, because their private fields differ. Implement a custom message matcher for projects that need to mock gRPCs can use.

See the passing tests in the following PRs for proof that this works as intended (which rely on a replace directive pointing to my fork of csi-test):

• Upgrade csi-spec to v1.10.0 with csi-test v3.5.1 protobuf fixes livenessprobe#296
• Upgrade CSI-Spec to v1.10.0 with csi-test v3.5.1 protobuf fixes external-health-monitor#277

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Will rebase other PRs in sidecar repositories once we release a new patch version of csi-test.

We should cherry-pick this to release-5.3.

Does this PR introduce a user-facing change?:

action required: If you are upgrading CSI spec to v1.10.0 and rely on mocking gRPC calls in your tests, you may need to use the csi-test utils package's Protobuf Matcher: `example.EXPECT().ExampleRequest(Protobuf(requestMsg)).Return(responseMsg, nil).AnyTimes()`

[gnufied]

/lgtm

[jsafrane]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: AndrewSirenko, jsafrane

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[AndrewSirenko]

/cherry-pick release-5.3