fix: not to throw error when no txs in block

[loin3]

Description

I followd this cosmos-sdk/issues/12040 and cosmos-sdk/pull/12108

our version 0.45.x does not have GetBlockWithTxs in x/auth/tx/service, so we create x/auth/tx2.
It's hard to cherr-pick because the directories are different. So I reflected the changes directly into tx2.

Motivation and context

When query through GetBlockWithTxs, invalid request error occurred when no txs are included in block.
The correct behavior is to return the block with empty list of txs.

How has this been tested?

tested no error occured and return 0 length of tx list

Screenshots (if appropriate):

before thsi PR, when tx does not exist in block

{
  "code": 3,
  "message": "out of range: cannot paginate 0 txs with offset 0 and limit 100: invalid request: invalid request",
  "details": []
}

when tx does not exist in block

{
  "txs": [],
  "block_id": {
    "hash": "tMvoEOdixC8Kt9YNwb6vGDsYJO/euSW3TRuDfzLijPk=",
    "part_set_header": {
      "total": 1,
      "hash": "ykh4pBbXq5ehsj2zyFRv0UdOFnf/8rVwjVl5MXN+pFM="
    }
  },
  "block": {
    "header": {
      "version": {
        "block": "11",
        "app": "0"
      },
      "chain_id": "simd-testing",
      "height": "115",
      "time": "2023-04-18T08:51:57.136998Z",
      "last_block_id": {
        "hash": "2mVthS8/78uoXxmNaQaO43UivRU142JD42xE/d3ps4I=",
        "part_set_header": {
          "total": 1,
          "hash": "ucOMMUTAhQtMR8sREYbbyG6RKKIDb3bOxjh5D/j1s0M="
        }
      },
      "last_commit_hash": "sUmrUkJM+xlOfckEN7yXVJX9zFySepZa2Gnl670tzwQ=",
      "data_hash": "47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=",
      "validators_hash": "wUFwitwdiD2JQIkDe4MofWg7YqGlxwofCZBWzI7H5Mk=",
      "next_validators_hash": "wUFwitwdiD2JQIkDe4MofWg7YqGlxwofCZBWzI7H5Mk=",
      "consensus_hash": "BICRvH3cKD93v7+R1zxE2ljD34qcvIZ0Bdi389qtoi8=",
      "app_hash": "39H866EPWyvnODRPEYFHFVXqdH+EJj03QpKADY12BGI=",
      "last_results_hash": "47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=",
      "evidence_hash": "47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=",
      "proposer_address": "VwWa2x8sslGSe+6MjgugQo0iGBA="
    },
    "data": {
      "txs": []
    },
    "evidence": {
      "evidence": []
    },
    "last_commit": {
      "height": "114",
      "round": 0,
      "block_id": {
        "hash": "2mVthS8/78uoXxmNaQaO43UivRU142JD42xE/d3ps4I=",
        "part_set_header": {
          "total": 1,
          "hash": "ucOMMUTAhQtMR8sREYbbyG6RKKIDb3bOxjh5D/j1s0M="
        }
      },
      "signatures": [
        {
          "block_id_flag": "BLOCK_ID_FLAG_COMMIT",
          "validator_address": "VwWa2x8sslGSe+6MjgugQo0iGBA=",
          "timestamp": "2023-04-18T08:51:57.136998Z",
          "signature": "lsvVrOiJqC8HzBR98fExYb32m4a+Hx2BtpeS8xu98EArSt7xM9Fni55jNujet85uWczriUFhUdPOf2zDEGyRBQ=="
        }
      ]
    },
    "entropy": {
      "round": 0,
      "proof": "A1AeRTirM3lC5QXH0DaCevHadrGw5WTRwOkOMytT5rDqUG19978T9wGAoR94pYQBYQ2DIHCI5QzyYAwTB6P8hqfULXBvsb8FAxvCKfjO6yQK"
    }
  },
  "pagination": {
    "next_key": null,
    "total": "0"
  }
}

Checklist:

• I followed the contributing guidelines and code of conduct.
• I have added a relevant changelog to CHANGELOG.md
• I have added tests to cover my changes.
• I have updated the documentation accordingly.
• I have updated API documentation client/docs/swagger-ui/swagger.yaml

[codecov-commenter]

Codecov Report

Merging #982 (ea6b6d8) into rc/v0.47.0-alpha1 (1c841d9) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

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Additional details and impacted files

@@                  Coverage Diff                  @@
##           rc/v0.47.0-alpha1     #982      +/-   ##
=====================================================
- Coverage              62.08%   62.08%   -0.01%     
=====================================================
  Files                    655      655              
  Lines                  79041    79041              
=====================================================
- Hits                   49076    49075       -1     
- Misses                 27283    27284       +1     
  Partials                2682     2682              

Impacted Files	Coverage Δ
x/auth/tx2/service.go	69.44% <100.00%> (ø)

... and 1 file with indirect coverage changes