Add transactionByHash selection to API

[vindard]

Description

If a user wants to get the details of a particular transaction, they currently have to call transactions and then iterate through all transactions until they find the one they want (e.g. from Alby).

We should somehow implement a transactionByHash selection to simplify this use-case. Ideally it would return a single "transaction summary" object with relevant information about the transaction instead of multiple ledger transactions that match the hash.

• #1210

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Related:

• #1203
• #1200