Add a staticcheck verify script and fix errors

[codenrhoden]

What this PR does / why we need it:
I figured since k/k now has support for running staticcheck, we should do it on our projects.

This patch adds a hack/verify-staticcheck.sh script, adds a Makefile
target for "make staticcheck", and fixes the errors found.

A couple of the other check scripts (format, lint) or modified to no
longer use GO111MODULE=off when they "go get" the needed tools. That
was there before to avoid having go.mod change when running the
scripts, but instead this patch just allows in the needed changes to
go.mod and the correct version should be installed every time. no need
to fight the tool. The go get commands are still needed in the
scripts, however, even if a go mod download has been done, because the
download won't install the tool, but go get will.

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

Special notes for your reviewer:
The initial list of errors found were:

cmd/vcpctl/provision/provision.go:40:2: var datacenter is unused (U1000)
cmd/vcpctl/provision/provision.go:42:2: var secretName is unused (U1000)
cmd/vcpctl/provision/provision.go:44:2: var secretNamespace is unused (U1000)
pkg/cli/cli.go:89:10: this value of err is never used (SA4006)
pkg/cli/user.go:44:2: field password is unused (U1000)
pkg/cloudprovider/vsphere/cloud.go:151:2: should merge variable declaration with assignment on next line (S1021)
pkg/common/config/config.go:438:4: this value of insecure is never used (SA4006)
pkg/common/connectionmanager/search.go:103:7: should omit comparison to bool constant, can be simplified to found (S1002)
pkg/common/connectionmanager/search.go:148:8: should omit comparison to bool constant, can be simplified to found (S1002)
pkg/common/connectionmanager/search.go:279:7: should omit comparison to bool constant, can be simplified to found (S1002)
pkg/common/connectionmanager/search.go:324:8: should omit comparison to bool constant, can be simplified to found (S1002)
pkg/common/connectionmanager/zones.go:178:7: should omit comparison to bool constant, can be simplified to found (S1002)
pkg/common/connectionmanager/zones.go:223:8: should omit comparison to bool constant, can be simplified to found (S1002)
pkg/common/connectionmanager/zones.go:330:36: should use make(map[string]string) instead (S1019)
pkg/common/vclib/pbm.go:68:6: should omit nil check; len() for nil slices is defined as zero (S1009)
pkg/common/vclib/utils.go:41:2: should use 'return <expr>' instead of 'if <expr> { return <bool> }; return <bool>' (S1008)
pkg/common/vclib/utils.go:130:15: should use raw string (`...`) with regexp.MustCompile to avoid having to escape twice (S1007)
pkg/common/vclib/virtualmachine.go:220:2: should replace loop with dsRefList = append(dsRefList, hostSystemMo.Datastore...) (S1011)
pkg/common/vclib/virtualmachine.go:292:3: should merge variable declaration with assignment on next line (S1021)

Release note:

NONE

/assign @andrewsykim
/assign @dvonthenen

[codenrhoden]

If we think this might cause conflicts with #241, let's wait on it until after that goes in.

Also, do we even think this is a good idea?

[davidvonthenen]

I think the "unused" stuff could be quite useful in helping remove dead/unreferenced code. The "should omit comparison to bool constant" is nit but meh.

I think the benefits of dead code removal is worth it.

[codenrhoden]

/hold
Will keep this held until David's PR goes in, so I can rebase and look for anything new.

[davidvonthenen]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dvonthenen

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[codenrhoden]

/hold cancel
@dvonthenen this is ready for your re-review. I rebased it after your new stuff went in.

[davidvonthenen]

/lgtm