Include "@deprecated" in generated TypeScript types

**Problem**
Currently the generated TypeScript types omit all deprecation information for fields. This makes it less obvious that client source code is using a deprecated field that should be removed.

**Suggested Solution**
Include `@deprecated` in the documentation block for deprecated field. This can be utilized by IDEs (such as VSCode) to mark the field as deprecated in the editor.

**Example**
Generated code:
```
/**
* Example of a deprecated field
* @deprecated
*/
deprecatedField: string | null;
```


No source file or test is named in the issue. Start by locating the TypeScript type-generation entry point and the handling of deprecated GraphQL fields; update the generated documentation block and verify that deprecated fields contain @deprecated in the output.

Written by the indexing model from the issue text.