Test nova json schemas

[Frost]

This adds the nova_json_schemas plugin, and a few tests for that as well.

Running the tests with NOVA_BRANCH=refs/tags/v0.12.1 rebar3 ct (because nova 0.13.x) currently does not work with nova_json_schemas procudes this output, highlighting the fact that the encoded JSON from the render_error/1 function in the plugin will generate an iolist which will then be encoded into json as a list of integers. This will be parsed and decoded by thoas as a list with a string.

I would really expect a binary string here, and it is probably a good idea if the encoded json can be parsed correctly by json implementations in other languages.

This is what it looks like in Python, for instance:

>>> s = "[{\"error_type\":[[119,114,111,110,103,95,116,121,112,101]],\"actual_value\":5,\"error_context\":\"schema_violation\",\"expected_value\":[\"a_string\"],\"field_info\":{\"type\":\"string\"}}]"
>>> json.loads(s)
[{'error_type': [[119, 114, 111, 110, 103, 95, 116, 121, 112, 101]], 'actual_value': 5, 'error_context': 'schema_violation', 'expected_value': ['a_string'], 'field_info': {'type': 'string'}}]

% NOVA_BRANCH=refs/tags/v0.12.1 rebar3 ct
===> Verifying dependencies...
===> Running erlydtl...
===> Analyzing applications...
===> Compiling nova_request_app
   ┌─ test/nova_request_app_fun_SUITE.erl:
   │
 3 │  -compile(export_all).
   │   ╰── Warning: export_all flag enabled - all functions will be exported

    ┌─ test/nova_request_app_fun_SUITE.erl:
    │
 35 │  end_per_suite(Config) ->
    │                ╰── Warning: variable 'Config' is unused


===> Cover compilation failed: {no_file_attribute,
                                       "/home/marfro/code/github/novaframework/nova_request_app/_build/test/lib/nova_request_app/ebin/nova_request_app_main_dtl.beam"}
===> Running Common Test suites...
=PROGRESS REPORT==== 7-Oct-2025::16:31:57.376029 ===
    supervisor: {local,logger_sup}
    started: [{pid,<0.774.0>},
              {id,cth_log_redirect},
              {mfargs,{gen_server,start_link,
                                  [{local,cth_log_redirect},
                                   cth_log_redirect,[],[]]}},
              {restart_type,transient},
              {significant,false},
              {shutdown,2000},
              {child_type,worker}]

%%% nova_request_app_SUITE: .....................
%%% nova_request_app_fun_SUITE: .......................
=DEBUG REPORT==== 7-Oct-2025::16:31:59.308101 ===
Got validation-errors on JSON body. Errors: [{data_invalid,
                                              #{<<"type">> => <<"string">>},
                                              wrong_type,5,
                                              [<<"a_string">>]}]
=DEBUG REPORT==== 7-Oct-2025::16:31:59.308361 ===
Rendering validation-errors and send back to requester

----------------------------------------------------
2025-10-07 16:31:59.322
Body: <<"[{\"error_type\":[[119,114,111,110,103,95,116,121,112,101]],\"actual_value\":5,\"error_context\":\"schema_violation\",\"expected_value\":[\"a_string\"],\"field_info\":{\"type\":\"string\"}}]">>
json:decode(Body): [#{<<"actual_value">> => 5,
                      <<"error_context">> => <<"schema_violation">>,
                      <<"error_type">> => ["wrong_type"],
                      <<"expected_value">> => [<<"a_string">>],
                      <<"field_info">> => #{<<"type">> => <<"string">>}}]



%%% nova_request_app_fun_SUITE ==> json_schema_validation_error: FAILED
%%% nova_request_app_fun_SUITE ==> {{badmatch,[#{<<"actual_value">> => 5,
              <<"error_context">> => <<"schema_violation">>,
              <<"error_type">> => ["wrong_type"],
              <<"expected_value">> => [<<"a_string">>],
              <<"field_info">> => #{<<"type">> => <<"string">>}}]},
 [{nova_request_app_fun_SUITE,json_schema_validation_error,1,
                              [{file,"/home/marfro/code/github/novaframework/nova_request_app/test/nova_request_app_fun_SUITE.erl"},
                               {line,254}]},
  {test_server,ts_tc,3,[{file,"test_server.erl"},{line,1796}]},
  {test_server,run_test_case_eval1,6,[{file,"test_server.erl"},{line,1305}]},
  {test_server,run_test_case_eval,9,[{file,"test_server.erl"},{line,1237}]}]}

EXPERIMENTAL: Writing retry specification at /home/marfro/code/github/novaframework/nova_request_app/_build/test/logs/retry.spec
              call rebar3 ct with '--retry' to re-run failing cases.
Failed 1 tests. Passed 44 tests. 
Results written to "/home/marfro/code/github/novaframework/nova_request_app/_build/test/logs/index.html".
===> Failures occurred running tests: 1

---

This is of course not really mergeable as is, since it has broken tests in it, but I still want to highlight the problem.