feat(jellyfish-api-core): add blockchain getTxOutSetInfo RPC (#1775)

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#### What this PR does / why we need it:
/kind feature

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Fixes part of #48 
- Implements `gettxoutsetinfo` type for RPC.

docs/node/CATEGORIES/01-blockchain.md

@@ -226,6 +226,28 @@ interface ScriptPubKey {
 }
 ```
 
+## getTxOutSetInfo
+
+Returns statistics about the unspent transaction output set.
+Note this call may take some time.
+
+```ts title="client.blockchain.getTxOutSetInfo()"
+interface blockchain {
+  getTxOutSetInfo (): Promise<TxOutSetInfo>
+}
+
+interface TxOutSetInfo {
+  height: number
+  bestblock: string
+  transactions: Number
+  txouts: Number
+  bogosize: Number
+  hash_serialized_2: string
+  disk_size: Number
+  total_amount: BigNumber
+}
+```
+
 ## getRawMempool
 
 Get all transaction ids in memory pool as string[] if verbose is false else as json object

packages/jellyfish-api-core/__tests__/category/blockchain/getTxOutSetInfo.test.ts

@@ -0,0 +1,32 @@
+import { MasterNodeRegTestContainer } from '@defichain/testcontainers'
+import { ContainerAdapterClient } from '../../container_adapter_client'
+import BigNumber from 'bignumber.js'
+
+describe('TxOutSetInfo', () => {
+  const container = new MasterNodeRegTestContainer()
+  const client = new ContainerAdapterClient(container)
+
+  beforeAll(async () => {
+    await container.start()
+    await container.waitForBlockHeight(1)
+  })
+
+  afterAll(async () => {
+    await container.stop()
+  })
+
+  it('should getTxOutSetInfo', async () => {
+    const txOutSetInfo = await client.blockchain.getTxOutSetInfo()
+
+    expect(txOutSetInfo).toStrictEqual({
+      height: 2,
+      bestblock: expect.any(String),
+      transactions: expect.any(Number),
+      txouts: expect.any(Number),
+      bogosize: expect.any(Number),
+      hash_serialized_2: expect.any(String),
+      disk_size: expect.any(Number),
+      total_amount: expect.any(BigNumber)
+    })
+  })
+})

packages/jellyfish-api-core/src/category/blockchain.ts

@@ -137,6 +137,18 @@ export class Blockchain {
     })
   }
 
+  /**
+   * Returns statistics about the unspent transaction output set.
+   * Note this call may take some time.
+   *
+   * @return {Promise<TxOutSetInfo>}
+   */
+  async getTxOutSetInfo (): Promise<TxOutSetInfo> {
+    return await this.client.call('gettxoutsetinfo', [], {
+      total_amount: 'bignumber'
+    })
+  }
+
   /**
    * Get all transaction ids in memory pool as string
    *
@@ -343,6 +355,17 @@ export interface UTXODetails {
   coinbase: boolean
 }
 
+export interface TxOutSetInfo {
+  height: number
+  bestblock: string
+  transactions: Number
+  txouts: Number
+  bogosize: Number
+  hash_serialized_2: string
+  disk_size: Number
+  total_amount: BigNumber
+}
+
 export interface ScriptPubKey {
   asm: string
   hex: string