Add txpool_inspect JSON-RPC method

[fab-10]

Summary

Stacks on top of #10120 (txpool_content), please review it first

Implements the spec-defined txpool_inspect JSON-RPC method. Returns a textual summary of all pending and queued transactions in the pool, grouped by sender address and nonce.
Some duplicated code was removed as part of this PR.

Since the content is free form and implementation dependent, Besu chose to return this output

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "pending": {
      "0x67ee9a8c19f7873125a875f61add461b4a505d8c": {
        "5": "{sequence: 68178, addedAt: 1775837774160, isLocal=false, hasPriority=false, score=127, 0xfbee0231c6140f9db3bbcef774b3626556f6f5528a6a49dcd38e1f7f86c79368={MessageCall, 5, 0x67ee9a8c19f7873125a875f61add461b4a505d8c, EIP1559, mf: 300.00 kwei, pf: 300.00 kwei, gl: 70926, v: 0 wei, to: 0xe9f8133e47d42bc9962e469721faaf75e385af31}}",
        "6": "{sequence: 68179, addedAt: 1775837774160, isLocal=false, hasPriority=false, score=127, 0x3474c0582722ed751dba809363f58c8d1acea415831b81bc0b0b9f29afb19c19={MessageCall, 6, 0x67ee9a8c19f7873125a875f61add461b4a505d8c, EIP1559, mf: 2.00 mwei, pf: 2.00 mwei, gl: 90617, v: 0 wei, to: 0x1eb4a2620b909a8838e0e24a8e912bd32f4a47a3}}"
      }
    },
    "queued": {
      "0x5fa84846743cc07ab16106ceabad8e4e0ec1c1b6": {
        "29": "{sequence: 2208499, addedAt: 1775952461706, isLocal=false, hasPriority=false, score=127, 0x2bb5f69f2b9737a99a3674018cd2aac5035b907a753a0c797051bc9df0b2a152={MessageCall, 29, 0x5fa84846743cc07ab16106ceabad8e4e0ec1c1b6, EIP1559, mf: 1.40 gwei, pf: 417.90 mwei, gl: 63209, v: 0 wei, to: 0xdac17f958d2ee523a2206206994597c13d831ec7}}",
        "31": "{sequence: 1766002, addedAt: 1775931135467, isLocal=false, hasPriority=false, score=127, 0xdd250f166c086412fae187ef52dfbe1c4ff9405818781ac50f89d67a77a2d432={MessageCall, 31, 0x5fa84846743cc07ab16106ceabad8e4e0ec1c1b6, EIP1559, mf: 47.74 gwei, pf: 9.28 gwei, gl: 21000, v: 0 wei, to: 0x5fa84846743cc07ab16106ceabad8e4e0ec1c1b6}}"
      }
    }
  }
}

Changes

• TxPoolInspect: RPC handler, extends AbstractTxPoolContent<String>; delegates the per-transaction summary to PendingTransaction.toTraceLog() (the spec does not enforce a specific free-text format)
• RpcMethod: added TX_POOL_INSPECT("txpool_inspect")
• TxPoolJsonRpcMethods: registered TxPoolInspect

The humanReadableView helper is static to allow the unbound method reference TxPoolInspect::humanReadableView, and package-private to allow direct unit testing.

Test plan

• TxPoolInspectTest — 6 unit tests: empty pool, humanReadableView delegation to toTraceLog(), all-pending, pending/queued split, result values are non-empty strings

🤖 Generated with Claude Code

[macfarla]

couple of nits and a query about TransactionPoolStatusResult class change