[v0.30] Index name swapping with the new method POST /swap-indexes

[brunoocasali]

This feature request is part of the new features introduced on Meilisearch v0.30.
Extracted from meilisearch/integration-guides#221.

Related to:

• issue: Index swap meilisearch#2750
• spec: Swap Indexes API specifications#192

This issue aims to make Meilisearch more production-ready by allowing the swap of indexes, and this feature should remove the possible downtimes.

• Add the POST /swap-indexes endpoint
• Add an indexSwap task type
• Add an indexes.swap API Key action
• Add a duplicate_index_found error.
• Add swaps in Tasks.details
• Add code sample swap_indexes_1 into this file
  This code sample should show an example of the corresponding curl command, but with swift code:

curl \
    -X POST 'http://localhost:7700/swap-indexes' \
    -H 'Content-Type: application/json' \
    --data-binary '[
      {
        "indexes": [
          "indexA",
          "indexB"
        ]
      },
      {
        "indexes": [
          "indexX",
          "indexY"
        ]
      }
    ]'