Add support for acv.addFormats

[TRoussel]

Is your feature request related to a problem? Please describe.
Since version 7, Ajv does not include formats defined by JSON Schema specification. Hence, "byte" data format is not part of ajv validator and reports an error if we try to validate a schema with such data format using Postman.

Describe the solution you'd like
This, and several other formats are provided by ajv-formats plugin.
Add this plugin to Postam to be able to validate schemas which define attributes of byte format (and all other formats part of the plugin)

Additional context
Error reported by ajv validator when using 'byte' data format : "unknown format "byte" is used in schema at path "#/foo/bar"