[microsoft/TypeScript] Release v3.8-rc - TypeScript 3.8.1 RC

DRANK

For release notes, check out the [release announcement](https://devblogs.microsoft.com/typescript/announcing-typescript-3-8-beta/). For the complete list of fixed issues, check out the * [fixed issues query for Typescript v3.8-rc](https://github.com/microsoft/TypeScript/issues?utf8=%E2%9C%93&q=is%3Aissue+milestone%3A%22TypeScript+3.8.1%22+is%3Aclosed+). * [fixed issues query for Typescript v3.8-beta](https://github.com/microsoft/TypeScript/issues?utf8=%E2%9C%93&q=is%3Aissue+milestone%3A%22TypeScript+3.8.0%22+is%3Aclosed+). Downloads are available on: * [npm](https://www.npmjs.com/package/typescript) * [Visual Studio 2017/2019](https://marketplace.visualstudio.com/items?itemName=TypeScriptTeam.typescript-38rc) ([Select new version in project options](https://github.com/Microsoft/TypeScript/wiki/Updating-TypeScript-in-Visual-Studio-2017)) * [NuGet package](https://www.nuget.org/packages/Microsoft.TypeScript.MSBuild)