[scala][http4s] fix escaping of reserved words for correct model dese…

[donilg]

There is an example of correct openAPI specification:

{
  "openapi": "3.0.0",
  "info": {
    "title": "Simple API",
    "description": "A simple API with GET and POST endpoints",
    "version": "1.0.0"
  },
  "servers": [
    {
      "url": "https://api.example.com/v1"
    }
  ],
  "paths": {
    "/users": {
      "get": {
        "summary": "Method that has models with a reserved word",
        "parameters": [
          {
            "name": "typeName",
            "in": "query",
            "description": "param",
            "required": true,
            "schema": {
              "type": "string",
              "enum": [
                "active",
                "inactive",
                "pending"
              ]
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Successful response",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/User"
                }
              }
            }
          }
        }
      }
    }
  },
  "components": {
    "schemas": {
      "User": {
        "type": "object",
        "properties": {
          "type": {
            "type": "string",
            "enum": [
              "active",
              "inactive",
              "pending"
            ]
          }
        },
        "required": [
          "type"
        ]
      }
    }
  }
}

JSON response is generated for this OpenAPI specification:

{"_type":"active"}

This is incorrect since we specified that the field should be named type, not _type.
I changed the escaping of reserved words to standard Scala backticks notation so that the JSON decoder could properly map the domain to JSON.

{"type":"active"}

PR checklist

• Read the contribution guidelines.
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  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

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Hello! 👋
I'd love to get your eyes on this PR when you have a moment.
Thanks in advance!

@clasnake (2017/07), @shijinkui (2018/01), @ramzimaalej (2018/03), @chameleon82 (2020/03), @Bouillie (2020/04) @Fish86 (2023/06)