Add API endpoint to restore a legacy wallet.

[jonathanknowles]

Context

This task will provide an API endpoint that allows users to restore a Byron wallet from a mnemonic sentence.

Decision

The API will provide an endpoint similar to the following:

/byron/wallets:
  post:
    operationId: postByronWallet
    tags: ["Wallets"]
    summary: Restore
    description: Restore a Byron wallet from a mnemonic sentence.
    parameters:
      - <<: *parametersBody
        schema: *ApiByronWalletPostData
    responses: *responsesPostByronWallet

Where types have definitions similar to the following:

ApiByronWalletPostData: &ApiByronWalletPostData
  type: object
  required:
    - name
    - mnemonic_sentence
    - passphrase
  properties:
    name: *walletName
    mnemonic_sentence: *byronWalletMnemonicSentence
    passphrase: *walletPassphrase

x-byronWalletMnemonicSentence: &byronWalletMnemonicSentence
  description: A list of mnemonic words
  type: array
  minItems: 12
  maxItems: 12
  items:
    type: string
    format: bip-0039-mnemonic-word{english}
  example:
    [ "squirrel", "material", "silly", "twice", "direct", "slush"
    , "pistol", "razor", "become", "junk", "kingdom", "flee"]

x-responsesPostByronWallet: &responsesPostByronWallet
  <<: *responsesErr400
  <<: *responsesErr405
  <<: *responsesErr406
  <<: *responsesErr409
  <<: *responsesErr415
  202:
    description: Accepted
    schema: *ApiByronWallet

Acceptance Criteria

Within the list of criteria below, a ticked criterion indicates that there is test coverage in the master branch to demonstrate that this criterion is satisfied.

• The API must support restoration of Byron wallets through a dedicated endpoint.
• After a successful restoration, calling getByronWallet with a restored wallet ID must succeed.
• After a successful restoration, the listByronWallets operation must include the restored wallet in the list it returns.
• After a successful restoration, calling getByronWallet with a restored wallet ID must succeed.
• After a successful restoration, calling postByronWallet again with the same mnemonic sentence should result in an error.

PR

Number	Base
#790	master
#817	master
#846	master

QA

• Build integration tests to check that all acceptance criteria are satisfied.

[piotr-iohk]

lgtm!