Search SDK: Fix bug that prevented infinite double values from deserializing

[bitsforthought]

Description

Prior to this change, it was impossible to retrieve Double values from Azure Search if they were equal to positive or negative infinity. This is because the SDK was relying on JSON.NET's default behavior, which is to expect "Infinity" or "-Infinity", respectively. However, this is not how these values are serialized according to OData V4. In OData, they are "INF" and "-INF", respectively. To fix this, I added a new DoubleConverter. I also added a bunch of test coverage around boundary values.

Notes: We are not bumping the version yet because there are other changes we need to make first. Also, this is 100% changes to custom code; There are no corresponding Swagger changes.

FYI @chaosrealm @seansaleh @Yahnoosh @mhko

This checklist is used to make sure that common guidelines for a pull request are followed.

• I have read the contribution guidelines.
• The pull request does not introduce breaking changes.

General Guidelines

• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

SDK Generation Guidelines

• If an SDK is being regenerated based on a new swagger spec, a link to the pull request containing these swagger spec changes has been included above.
• The generate.cmd file for the SDK has been updated with the version of AutoRest, as well as a link to the swagger spec, used to generate the code.
• The project.json and AssemblyInfo.cs files have been updated with the new version of the SDK.

[chaosrealm]

LGTM