Add @exodus/schemasafe

[ChALkeR]

Things to note:

1. allowUnusedKeywords is required because that's what specification is expecting, and there are tests for that. By default, @exodus/schemasafe instead refuses to compile a schema with unused keywords to prevent failing in open state on e.g. schema author mistakes -- similar to how ajv behaves with strictKeywords option, but with deeper checks.

   That option does not affect the produced code or performance, it just affects whether the schema would be refused to compile or not.

2. Structured reporting is disabled by default, instead just a boolean validation status is reported — because if the user wants errors, they would enable them, and if they don't need errors and need just the result — they might forget to disable it for performance.

   I'm not sure how fair is that to other validators in this benchmark. If it's not -- just add includeErrors: true, to the options ;-)

3. Default $schema value is needed because $schema is not specified in all tests, and behavior differs between various spec versions. Specifically, $ref behavior changed in draft2019-09, and there is a test for that. Out of those two, draft2019-09 behavior is more secure and makes more sense, hence that's the default in schemasafe unless $schema is specified in the schema or $schemaDefault is specified in options.

[ebdrup]

1. In general I've tried to run all validators with their default settings, so as to avoid the benchmark being run with weird perfomance tweaks that do not make sense in the real world. This setting seems to be ok to use as per your explanation.
2. Following the principle of running the validator with default settings, this seems fine.
3. That's ok as far as I can see.

[ebdrup]

I general I use * for the latest stable version. This should be changed once you reach a stable v1.