[cpp-restsdk] Support multi-line descriptions

Created by: Peaches491

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh and ./bin/security/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\.
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Description of the PR

Using the YAML multi-line string notation will cause cpp-rest-sdk codegen to fail, with the newlines making it into the generated code:

  /job/:
    post:
      summary: "Adds a Job object to the Foo tool."
      operationId: "addJob"
      consumes:
      - "application/json"
      parameters:
      - in: "body"
        name: "fullJobDetails"
        description: |
          "JSON that contains all information needed to create a job for
           FooAPI."
        required: true
        schema:
          $ref: "#/definitions/FullJobDetails"

Yields:

    /// <summary>
    /// \&quot;Updates an ImageAttachment\&quot;·
    /// </summary>
    /// <remarks>
    ///·
    /// </remarks>
    /// <param name="fullJobDetails">\&quot;JSON that contains all information needed to create a job for
           FooAPI.\&quot; </param>
    pplx::task<std::shared_ptr<ImageFrameAttachment>> updateImageWithId(
        utility::string_t imageId,
        std::shared_ptr<ImageFrameAttachment> imageFrameAttachment
    ) override;

The uncommented FooAPI.\&quot; </param>, causes a compilation error.

This PR adds escapeText to all references to the numerous description references across DefaultCodegen.java