Bug 20942: Unit tests for /patrons/{patron_id}/account

Bug 20942: Unit tests for /patrons/{patron_id}/account

This patch adds tests for the /patrons/{patron_id}/account endpoint.
To test:

- Run:
  $ kshell
 k$ prove t/db_dependent/api/v1/patrons_accounts.t
=> FAIL: Tests should fail because the endpoint is not implemented.

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit 7cbff1bce1608016e8b8ceded7633678189b75cc)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>