feat(kumactl): inspect api support

[lobkovilya]

Summary

Current PR introduces new commands for kumactl that enable people to use Inspect API.
New commands:

• $ kumactl inspect dataplane NAME – see what policies were applied for the DPP
• $ kumactl inspect dataplane NAME --config-dump – see envoy config dump for DPP
• $ kumactl inspect zoneingress NAME --config-dump – see envoy config dump for ZoneIngress
• $ kumactl inspect POLICY NAME -- see what DPPs are affected by policy

Full changelog

• introduce new kumactl commands
• enable Inspect API e2e tests

Issues resolved

Fix #3730

Documentation

• Link to the website documentation PR WIP

Testing

• Unit tests
• E2E tests
• Manual testing on Universal
• Manual testing on Kubernetes

Backwards compatibility

- [ ] Update UPGRADE.md with any steps users will need to take when upgrading.
- [ ] Add backport-to-stable label if the code follows our backporting policy

[codecov-commenter]

Codecov Report

Merging #3805 (576c1a0) into master (b015316) will decrease coverage by 0.05%.
The diff coverage is 40.93%.

@@            Coverage Diff             @@
##           master    #3805      +/-   ##
==========================================
- Coverage   55.86%   55.81%   -0.06%     
==========================================
  Files         901      907       +6     
  Lines       53554    53747     +193     
==========================================
+ Hits        29920    29999      +79     
- Misses      21248    21338      +90     
- Partials     2386     2410      +24     

Impacted Files	Coverage Δ
.../kumactl/pkg/resources/dataplane_inspect_client.go	0.00% <0.00%> (ø)
app/kumactl/pkg/resources/policy_inspect_client.go	0.00% <0.00%> (ø)
...umactl/pkg/resources/zoneingress_inspect_client.go	0.00% <0.00%> (ø)
app/kumactl/pkg/cmd/root_context.go	58.69% <40.00%> (-2.28%)	⬇️
app/kumactl/cmd/inspect/inspect_zoneingress.go	40.90% <40.90%> (ø)
app/kumactl/cmd/inspect/inspect_dataplane.go	60.00% <60.00%> (ø)
pkg/api-server/types/inspect.go	76.47% <64.70%> (-5.89%)	⬇️
app/kumactl/cmd/inspect/inspect_policy.go	83.78% <83.78%> (ø)
app/kumactl/cmd/inspect/inspect.go	82.60% <100.00%> (+3.66%)	⬆️
pkg/plugins/runtime/gateway/route/sorter.go	61.53% <0.00%> (-10.26%)	⬇️
... and 11 more

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[lahabana]

Sweet!