feat: update schema specification with JSON schema validation

[kklimonda-cl]

Description

A new schema for API specifications, along with JSON schema files that can
be used to validate specification, and runtime conversion of new schema
to the old one to avoid large changes across our codegen templates.

Motivation and Context

Existing specification had some edge cases that made writing codegen more complicated:

• maps were used as lists making every object not self-contained
• parameters that were objects had no type
• it was possible to access any parameter data without checking if it is valid for the given parameter type (eg. checking items type for simple specs)
• validation rules for parameters, locations, entries were flattened into the parent objects
• golang templates were directly referenced in entries

New schema solves those and some other issues, and removes codegen-level data (like NameVariants) that will be implemented in the Sdk and Terraform marshallers.

How Has This Been Tested?

Screenshots (if appropriate)

Types of changes

• New feature (non-breaking change which adds functionality)