feat: add Konnect client & move tls cert extract to util

[randmonkey]

What this PR does / why we need it:

• Add a Konnect client to call APIs not inside Kong client. Currently node APIs.
• upload status of node for KIC itself in Konnect

Which issue this PR fixes:

expected to fix #3438

Special notes for your reviewer:

This PR will only include updating nodes for KIC itself to Konnect to avoid it being too large. works for uploading status of managed kong gateway nodes are tracked in issue #3501.

Includes extracting code for getting TLS cert into internal/util/tls package. If this change is useful, I'll consider move the change to a separate PR.

PR Readiness Checklist:

Complete these before marking the PR as ready to review:

• the CHANGELOG.md release notes have been updated to reflect any significant (and particularly user-facing) changes introduced by this PR

[codecov]

Codecov Report

Base: 73.8% // Head: 72.8% // Decreases project coverage by -1.1% ⚠️

Coverage data is based on head (d6afa98) compared to base (bbb70b7).
Patch coverage: 8.0% of modified lines in pull request are covered.

❗ Current head d6afa98 differs from pull request most recent head f1e911d. Consider uploading reports for the commit f1e911d to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #3469     +/-   ##
=======================================
- Coverage   73.8%   72.8%   -1.1%     
=======================================
  Files        116     119      +3     
  Lines      13883   14099    +216     
=======================================
+ Hits       10258   10272     +14     
- Misses      2962    3167    +205     
+ Partials     663     660      -3     

Impacted Files	Coverage Δ
internal/adminapi/konnect.go	0.0% <0.0%> (ø)
internal/adminapi/tls.go	100.0% <ø> (+41.3%)	⬆️
internal/konnect/client.go	0.0% <0.0%> (ø)
internal/konnect/node_agent.go	0.0% <0.0%> (ø)
internal/manager/run.go	45.1% <0.0%> (-2.9%)	⬇️
internal/util/tls/tls_cert.go	55.5% <55.5%> (ø)
internal/adminapi/kong.go	61.1% <100.0%> (+1.1%)	⬆️
...nternal/controllers/gateway/udproute_controller.go	71.6% <0.0%> (-2.2%)	⬇️
internal/dataplane/parser/parser.go	90.0% <0.0%> (-0.7%)	⬇️
... and 3 more

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[czeslavo]

IMO from the functional perspective this PR might be already merged. We'd just need to create tracking issues for all the TODOs left here and there (handling the task shutdown, parsing error response, etc.).

[pmalek]

I also feel that we can merge this but I'd prefer to remove all those TODOs with references to issues created in this repo.

[randmonkey]

I also feel that we can merge this but I'd prefer to remove all those TODOs with references to issues created in this repo.

put the followups into 2 issues:

• updating status of KIC node: KIC-Konnect: update status of KIC node #3515
• updating status of controlled kong gateway nodes: KIC-Konnect: collect and upload status of controlled kong gateway instances to Konnect #3501

comments are resolved