feat: add user impersonation to all commands

[logan-bobo]

What this PR does / why we need it:

Fixes # #547

Working configuration after adding the --as flag for user impersonation.

./bin/kubectl-kuttl test --config ... --as admin
=== RUN   kuttl
    harness.go:464: starting setup
    harness.go:255: running tests using configured kubeconfig.
    harness.go:278: Successful connection to cluster at:...
    harness.go:363: running tests
    harness.go:75: going to run test suite with timeout of 30 seconds for each step
    harness.go:375: testsuite: ...
=== RUN   kuttl/harness
=== RUN   kuttl/harness/00-check-deploy
=== PAUSE kuttl/harness/00-check-deploy
=== CONT  kuttl/harness/00-check-deploy
    logger.go:42: 19:45:28 | 00-check-deploy | Creating namespace: kuttl-test-engaged-cockatoo
    logger.go:42: 19:45:28 | 00-check-deploy/0- | starting test step 0-
    logger.go:42: 19:45:29 | 00-check-deploy/0- | test step completed 0-
    logger.go:42: 19:45:29 | 00-check-deploy | skipping kubernetes event logging
    logger.go:42: 19:45:29 | 00-check-deploy | Deleting namespace: kuttl-test-engaged-cockatoo
=== NAME  kuttl
    harness.go:407: run tests finished
    harness.go:515: cleaning up
    harness.go:572: removing temp folder: ""
--- PASS: kuttl (7.71s)
    --- PASS: kuttl/harness (0.00s)
        --- PASS: kuttl/harness/00-check-deploy (7.16s)
PASS

Without having user impersonation

❯ ./bin/kubectl-kuttl test --config ...
=== RUN   kuttl
    harness.go:464: starting setup
    harness.go:255: running tests using configured kubeconfig.
    harness.go:278: Successful connection to cluster at:...
    harness.go:363: running tests
    harness.go:75: going to run test suite with timeout of 30 seconds for each step
    harness.go:375: testsuite:...
=== RUN   kuttl/harness
=== RUN   kuttl/harness/00-check-deploy
=== PAUSE kuttl/harness/00-check-deploy
=== CONT  kuttl/harness/00-check-deploy
    logger.go:42: 19:47:44 | 00-check-deploy | Creating namespace: kuttl-test-awaited-dingo
    case.go:357: namespaces is forbidden: User "" cannot create resource "namespaces" in API group "" at the cluster scope
    logger.go:42: 19:47:44 | 00-check-deploy | Deleting namespace: kuttl-test-awaited-dingo
    case.go:117: namespaces "kuttl-test-awaited-dingo" is forbidden: User "" cannot delete resource "namespaces" in API group "" in the namespace "kuttl-test-awaited-dingo"
=== NAME  kuttl
    harness.go:407: run tests finished
    harness.go:515: cleaning up
    harness.go:572: removing temp folder: ""
--- FAIL: kuttl (0.84s)
    --- FAIL: kuttl/harness (0.00s)
        --- FAIL: kuttl/harness/00-check-deploy (0.31s)
FAIL

[logan-bobo]

I have managed to pass the as flag down to the two types of client that are created Client and DiscoveryClient please let me know what you think of the approach and I will add the remaining commands.

[porridge]

I'm afraid plumbing this and related flags all the way this way is not going to be very sustainable 😟 ).

Can we try keeping the Client signature unchanged? I'm AFK so cannot easily check everything, but see an idea in an inline comment.

[porridge]

Excellent, this looks really neat!

Can you please:

• also change the call in Harness.Config
• make sure you update docs/
• since this is not very testable without specific cluster configuration, please copy-paste into PR description some terminal output showing how this fails without the option and works with it

[porridge]

Excellent ❤️
Just a few more nitpicks..

[porridge]

Ah, 💩
I applied my nitpicks to save some back-and-forth and forgot that this will break the DCO check 🤦🏻
And now I cannot fix it easily because I cannot push to your fork. Please help! 😅

[logan-bobo]

@porridge I will apply these and sign them

[logan-bobo]

@porridge all of your comments have been added to the latest commit 🤝