Add eksctl support to e2e scripts

[wongma7]

Is this a bug fix or adding new feature? testing

What is this PR about? / Why do we need it? Would like to test the driver on eks in addition to kops. eksctl command is similar enough to kops that I think the easiest way is to add a short eksctl script (eksctl.sh) like kops.sh

implementation detail differences:

• eksctl doesn't have an equivalent to 'kops export kubecfg' to export kubeconfig and (re) set the current-context to the test cluster. I refactored the scripts such that they export kubeconfig to a file in the test dir instead of .kube/config so that it's easier to keep track of them and to avoid polluting .kube/config
• I haven't figured out yet how to patch eksctl clujster config to add node iam policies, I think first I will add an eks prow job and then work on adding it in a future PR.
• K8S_VERSION must be x.y for eksctl not x.y.z as for kops.
• eksctl doesn't have an equivalent to kops update --yes. for kops, first you update the state file in s3 then run update --yes to actually update the cluster resources, eksctl it happens at once, there is no state file?

What testing is done?
tested locally:

$ TEST_ID=88888 \
                                              CLEAN=true \
                                              CLUSTER_TYPE=eksctl \
                                              GINKGO_NODES=1 \
                                              AWS_REGION=us-west-2 \
                                              AWS_AVAILABILITY_ZONES=us-west-2a,us-west-2b,us-west-2c \
                                              TEST_PATH=./tests/e2e-kubernetes/... \
                                              GINKGO_FOCUS="asdf" \
                                              K8S_VERSION="1.19" \
                                              ./hack/e2e/run.sh
...
2021-04-26 12:52:35 [ℹ]  will delete stack "eksctl-test-cluster-88888-k8s-local-cluster"
2021-04-26 12:52:35 [✔]  all cluster resources were deleted
###
## OVERALL_TEST_PASSED: 0
#
###
## SUCCESS!
#

Will let CI test that i haven't broken the existing kops job. Will add an eks prow job later and then work on fixing it in future PR.

[k8s-ci-robot]

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This pull-request has been approved by: wongma7

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[wongma7]

this is unrelated change, cuz I found out while testing "kops update cluster --state "${KOPS_STATE_FILE}" "${CLUSTER_NAME}"
--ssh-public-key="${SSH_KEY_PATH}".pub --yes" is deprecated:

--ssh-public-key string SSH public key to use (deprecated: use kops create secret instead)

[coveralls]

Pull Request Test Coverage Report for Build 1932

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 17 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.06%) to 79.188%

---

Files with Coverage Reduction	New Missed Lines	%
pkg/cloud/metadata.go	17	83.48%

Totals
Change from base Build 1890:	-0.06%
Covered Lines:	1990
Relevant Lines:	2513

---

💛 - Coveralls

[nckturner]

Nice, some small comments.

[nckturner]

/lgtm

[wongma7]

coveralls bugged (did not touc hgo code), manual merge