Update the API to be more friendly with swagger

The next endpoints need to be changed in order of be more swagger friendly, this will only add some features to the api, and set in a proper way according to openapi standard and generator capacities.
The endpoints are:
- [ ] /api/v1/block -> /api/v1/block and /api/v1/block/verbose
- [ ] /api/v1/blocks -> /api/v1/blocks and /api/v1/blocks/verbose
- [ ] /api/v1/transaction -> /api/v1/transaction, /api/v1/transaction/verbose and /api/v1/transaction/encoded
- [ ] /api/v1/transactions -> /api/v1/transactions and /api/v1/transactions/verbose
- [ ] /api/v1/wallet/transactions -> /api/v1/wallet/transactions and /api/v1/wallet/transactions/verbose
- [ ] /api/v2/transaction -> /api/v2/transaction and /api/v2/transaction/unspent
- [ ] /api/v2/data -> /api/v2/data and /api/v2/data/single
- [ ] /api/v1/pendingTxs -> /api/v1/pendingTxs and /api/v1/pendingTxs/verbose
- [ ] /api/v1/last_blocks -> /api/v1/last_blocks and /api/v1/last_blocks/verbose

The struct is `endpoint -> transformations`

Start by locating the handlers and OpenAPI definitions for the listed /api/v1 and /api/v2 endpoints. Compare their current representations with the issue's endpoint-to-transformation mapping. Done means all listed transformations are exposed as OpenAPI-compatible, generator-friendly routes; the issue names no tests.

Written by the indexing model from the issue text.