Include rawstring delimiters in the tree, use for injections

In raw-strings, the delimiter can be used to indicate embedded language:

   R"css( body { background: red; } )css"

This patch adds the delimiter (if present) and raw-string content as
children of the raw_string_literal.

These can be used to parse the content with an injected grammar.

Fixes https://github.com/tree-sitter/tree-sitter-cpp/issues/159

With the rise in supply chain attacks and OSS dependencies being used as a attack vector, Microsoft is working with our ecosystem partners, such as the Linux Foundation's OpenSSF, to enable OSS consumers to track packages back to their public sources.
We've identified that the following packages published to NPM do not report where sources can be found, typically accomplished by including a link to your GitHub repository in your `package.json` REPOSITORY field. This PR was created to add this value, ensuring future releases will include this provenance information.
Published NPM packages with repository information:
* tree-sitter-cpp

* Add support for Microsoft-specific modifiers

Microsoft-specific modifiers are keywords can be used to modify declarators to form derived types.

The specification for the modifiers themselves is here:
https://docs.microsoft.com/en-us/cpp/cpp/microsoft-specific-modifiers?view=vs-2019

This commit updates tree-sitter-c to ^0.16.1 that supports the modifiers
, updates the grammar.js to reflect the changes and add tests.

* 0.16.1

Refs atom/language-c#326

Fixes #23