Use node wrapper to debug NodeJS apps

[briandealwis]

Fixes: #2170

Description

Cause NodeJS apps to use the newly-introduced node wrapper.

Many applications use NodeJS-based tools as part of their launch, like npm, rather than
invoke node directly. These intermediate node instances may interpret the
--inspect arguments. GoogleContainerTools/container-debug-support#34 introduced a node wrapper that only passes --inspect when provided an application script, and otherwise propagates --inspect via an environment variable.

One other minor change: this now sorts the environment variables when populating the k8s Container objects to make comparisons stable in the tests.

User facing changes

NodeJS apps that previously seemed undebuggable should now respond to debugging treatment.

[codecov]

Codecov Report

Merging #4086 into master will increase coverage by 0.02%.
The diff coverage is 81.25%.

Impacted Files	Coverage Δ
pkg/skaffold/debug/transform_nodejs.go	78.63% <81.25%> (+0.56%)	⬆️
...affold/kubernetes/portforward/kubectl_forwarder.go	68.29% <0.00%> (+2.43%)	⬆️

[nkubala]

so if I understand correctly, /dbg/nodejs/bin was added to the debug helper image in GoogleContainerTools/container-debug-support#34. but that image tag wasn't bumped anywhere here - where is that referenced in skaffold? i'm wondering if we integration tests that run in CI to make sure nothing in this image changes out from under our feet.

[briandealwis]

We live at latest. There are tests in integration/testdata/debug for nodejs and npm. They wait for the deployments to be stable. Hmm, I should define some readiness probes there.