cluster-ui: create transaction details api

Currently the transaction overview and details (fingerprint) pages use the same API. This request/response shows the top x transactions by the requested sort and limit params. There are places in the console however where we want to look up arbitrary transaction fingerprints, not necessarily one that would be returned by that request (e.g. from the insights page, or perhaps from a statement details page where its txn wouldn't show up with the request/limit params sent).

We need a separate transaction details api to allow retrieving txn details for a single txn fingerprint (optionally by application). This new api can use the sql over http api. We already have something like this for statement details.

Jira issue: CRDB-30514

Epic CRDB-39643