Add admin key to get /network/nodes endpoint

[sdimitrov9]

Description:
Adding admin_key to the get /network/nodes REST API

Related issue(s):

Fixes #8757

Notes for reviewer:

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.27%. Comparing base (0c38f14) to head (b89ce25).
Report is 28 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #9776      +/-   ##
============================================
+ Coverage     92.23%   92.27%   +0.04%     
- Complexity     7628     7770     +142     
============================================
  Files           937      951      +14     
  Lines         32117    32457     +340     
  Branches       4071     4113      +42     
============================================
+ Hits          29622    29951     +329     
+ Misses         1542     1541       -1     
- Partials        953      965      +12     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests
• JS Bundle Analysis - Avoid shipping oversized bundles

[SvetBorislavov]

Hey, the 'admin_key' value structure is not correct. The node's admin_key is of type 'Key', here is the definition inside the protobuf: https://github.com/hashgraph/hedera-protobufs/blob/main/services/state/addressbook/node.proto#L148
The mirror node currently returns this kind of 'Key' structure in the following format:

"key": {
        "_type": "ED25519",
        "key": "61f37fc1bbf3ff4453712ee6a305c5c7255955f7889ec3bf30426f1863158ef4"
      }

This is an example of the /accounts response:
Here is the whole request: https://testnet.mirrornode.hedera.com/api/v1/accounts?account.id=2159149

The structure should be such because the key may be a KeyList with multiple levels.

The key type is also shown in the screenshot you have attached.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[steven-sheehy]

LGTM

[edwin-greene]

Looks good