Faster image-push command

[divolgin]

What this PR does / why we need it:

This makes the kots admin-console push-images command run faster:

1. Initial bundle scan needed to create progress page in UI is skipped when CLI is used
2. Images are extracted and pushed in parallel instead of sequential "extract" -> "push" chain of steps.
3. The final scan of the bundle that looks for Embedded Cluster images is terminated early if there are no Embedded Cluster resources in the bundle.
4. But if there are Embedded Cluster images, they are processed in parallel with application images.

Testing with a 160GB airgap bundle, timing before:

$ time kots admin-console push-images ./67.airgap 34.133.154.238:5000
...
real	142m48.808s
user	187m47.327s
sys	22m15.314s

with gzip and sequential image push

$ time kots admin-console push-images ./67.airgap 34.133.154.238:5000
...
real	50m10.771s
user	109m0.847s
sys	14m39.375s

with pgzip and podman's ConcurrentBlobCopiesSemaphore

$ time kots admin-console push-images ./67.airgap 34.133.154.238:5000
...
real	37m24.219s
user	106m45.268s
sys	15m20.171s

Which issue(s) this PR fixes:

Does this PR require a test?

Does this PR require a release note?

New features:

Bug fixes:

Improvements:

Improves the speed of the `kots admin-console push-images` command

Does this PR require documentation?

[greptile-apps]

_{Reviews (1): Last reviewed commit: "Faster image-push command" | Re-trigger Greptile}

[greptile-apps]

_{Reviews (2): Last reviewed commit: "double memory for pgzip" | Re-trigger Greptile}