Ledger: Use representative for change blocks and epoch signer for epoch blocks in linked_account

[Exxenoz]

• For change blocks, ledger::linked_account now returns the block's representative
• For epoch blocks, it returns the corresponding epoch signer

Issues resolved
This PR is an extension to PR #4841

This PR simplifies the detection of related accounts for block explorer applications. As a result, the following logic can be completely removed, reducing complexity:

switch (historyEntry.type) {
  case "change":
	relatedAccount = historyEntry.representative;
	break;
  case "open":
  case "receive":
	relatedAccount = historyEntry.account;
	break;
  case "send":
	relatedAccount = historyEntry.destination;
	break;
  case "state":
	switch (historyEntry.subtype) {
	  case "change":
		relatedAccount = historyEntry.representative;
		break;
	  case "epoch": // ToDo: Find epoch signer
		relatedAccount = historyEntry.account;
		break;
	  case "receive":
	  case "send":
		relatedAccount = historyEntry.account;
		break;
	}
	break;
}

[gr0vity-dev-bot]

Test Results for Commit 6de112d

Pull Request 4842: Results
Overall Status: ✅

Test Case Results

• ✅ 5n4pr_conf_10k_bintree: PASS (Duration: 106s)
• ✅ 5n4pr_conf_10k_change: PASS (Duration: 195s)
• ✅ 5n4pr_conf_change_dependant: PASS (Duration: 120s)
• ✅ 5n4pr_conf_change_independant: PASS (Duration: 126s)
• ✅ 5n4pr_conf_send_dependant: PASS (Duration: 111s)
• ✅ 5n4pr_conf_send_independant: PASS (Duration: 127s)
• ✅ 5n4pr_rocks_10k_bintree: PASS (Duration: 114s)
• ✅ 5n4pr_rocks_10k_change: PASS (Duration: 140s)

Last updated: 2025-02-09 17:54:06 UTC

[Exxenoz]

It's about this commit: 6de112d

Can someone tell me if this makes sense? If so, I'll do a rebase and fix the web socket tests; otherwise the PR can be closed.