JSON schema improvements - Add constraints, enum values

[floydtree]

The current json-schema, e.g. https://schema.ocsf.io/schema/1.3.0/objects/network_endpoint doesn't include the data-type constraints defined in the dictionary - https://github.com/ocsf/ocsf-schema/blob/main/dictionary.json#L4839.

These constraints are in the form of regex, max_length, range and values. All these can be represented in the json-schema that is rendered by our server, helping json-schema based validation use-cases and perform value specific validation. JSON spec has a few built-in string formats that can be leveraged as well.

Further, we can also add constant values for attributes such as class_name, category_name etc, as we render the json-schema of an event class.

References -

1. https://json-schema.org/understanding-json-schema/reference/const
2. https://json-schema.org/understanding-json-schema/reference/regular_expressions
3. https://json-schema.org/understanding-json-schema/reference/string
4. https://json-schema.org/understanding-json-schema/reference/numeric#range

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We should also include "additionalProperties": false, key in the generated schema to make validation use-cases more feasible. (for each object definition and the event class definition) #112

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The string sibling values should also be added as an enum for the corresponding properties

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Add requirements based on OCSF "constraints"