Validate: bug fixes

[mhuang74]

• fix output count with --fail-fast
• gracefully handle when csv input has no headers, or headers don't match what's in schema file
• change suffix to validation-errors.jsonl since it only contains errors
• removed 1 layer of If statement and shifted code left, and seems diff is quite confused and highlights huge blocks of code in red
• add integration test coverage for validation-error.jsonl contents
• add Adur Public Toilets example to Validate.md

mhuang@twisted-linen:~/Projects/rust/qsv (validate-bug-fixes)$ cargo test validate 
    Finished test [optimized + debuginfo] target(s) in 0.37s
     Running unittests (target/debug/deps/qsv-eb284739a6602195)

running 5 tests
test cmd::validate::tests_for_csv_to_json_conversion::test_to_json_instance_cast_integer_error ... ok
test cmd::validate::tests_for_csv_to_json_conversion::test_to_json_instance ... ok
test cmd::validate::tests_for_schema_validation::test_validate_with_error ... ok
test cmd::validate::tests_for_schema_validation::test_validate_with_no_errors ... ok
test cmd::validate::test_load_json_via_url ... ok

test result: ok. 5 passed; 0 failed; 0 ignored; 0 measured; 7 filtered out; finished in 1.84s

     Running unittests (target/debug/deps/qsvlite-8b35491d819e71f9)

running 5 tests
test cmd::validate::tests_for_csv_to_json_conversion::test_to_json_instance ... ok
test cmd::validate::tests_for_csv_to_json_conversion::test_to_json_instance_cast_integer_error ... ok
test cmd::validate::tests_for_schema_validation::test_validate_with_no_errors ... ok
test cmd::validate::tests_for_schema_validation::test_validate_with_error ... ok
test cmd::validate::test_load_json_via_url ... ok

test result: ok. 5 passed; 0 failed; 0 ignored; 0 measured; 7 filtered out; finished in 0.33s

     Running tests/tests.rs (target/debug/deps/tests-3f2bfc931ef0ab18)

running 3 tests
test test_validate::validate_bad_csv ... ok
test test_validate::validate_good_csv ... ok
test test_validate::validate_adur_public_toilets_dataset_with_json_schema ... ok

test result: ok. 3 passed; 0 failed; 0 ignored; 0 measured; 624 filtered out; finished in 0.04s

[jqnatividad]

@mhuang74 went ahead and merged the PR, rancargo fmt, and corrected a small typo.

I like how you tweaked the JSON schema test to exercise jsonschema's validation capabilities. 💯 😄

Ran cargo clippy but decided not to apply the recommendations this time. I typically run both rustfmt and clippy as SOP.

warning: unnecessary closure used to substitute value for `Option::None`
   --> src\cmd\validate.rs:297:25
    |
297 |           let field_def = schema_properties
    |  _________________________^
298 | |             .get(&header_string)
299 | |             .unwrap_or_else(|| &Value::Null);
    | |____________________________________________^
    |
    = note: `#[warn(clippy::unnecessary_lazy_evaluations)]` on by default
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_lazy_evaluations
help: use `unwrap_or` instead
    |
297 ~         let field_def = schema_properties
298 ~             .get(&header_string).unwrap_or(&Value::Null);
    |

warning: unnecessary closure used to substitute value for `Option::None`
   --> src\cmd\validate.rs:301:30
    |
301 |         let field_type_def = field_def.get("type").unwrap_or_else(|| &Value::Null);
    |                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `unwrap_or` instead: `field_def.get("type").unwrap_or(&Value::Null)`     
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_lazy_evaluations

warning: unnecessary closure used to substitute value for `Option::None`
   --> src\cmd\validate.rs:303:25
    |
303 |         let json_type = field_type_def.as_str().unwrap_or_else(|| "string");
    |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `unwrap_or` instead: `field_type_def.as_str().unwrap_or("string")`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_lazy_evaluations

warning: `qsv` (bin "qsvlite") generated 3 warnings (3 duplicates)
warning: `qsv` (bin "qsv") generated 3 warnings
    Finished dev [unoptimized + debuginfo] target(s) in 7.94s

If you decide not to follow the clippy recommendations, can you add #[allow(clippy:unnecessary_lazy_evaluations)] before those lines?