Support prettier-ignore-start/end for other languages (not only Markdown)

It seems this feature was added only for markdown (#4202 cc @ikatyang), but it's actually useful for other languages as well. It is not working on typescript files on my tests.

Related: https://github.com/facebook/create-react-app/issues/5543

Environments:

• Prettier Version: 1.14.3
• Running Prettier via: CLI
• Runtime: Node.js v8.11.4
• Operating System: macOS

Steps to reproduce:

Create a index.d.ts file with the following content:

// prettier-ignore
type A1 = string;

// prettier-ignore
type A2 = string

/* prettier-ignore-start */
type B1 = string;
type B2 = string
/* prettier-ignore-end */

type C1 = string;
type C2 = string

Expected behavior:

// prettier-ignore
type A1 = string;

// prettier-ignore
type A2 = string

/* prettier-ignore-start */
type B1 = string;
type B2 = string
/* prettier-ignore-end */

-type C1 = string;
+type C1 = string
type C2 = string

Actual behavior:

// prettier-ignore
type A1 = string;

// prettier-ignore
type A2 = string

/* prettier-ignore-start */
-type B1 = string;
+type B1 = string
type B2 = string
/* prettier-ignore-end */

-type C1 = string;
+type C1 = string
type C2 = string

Start by reproducing the issue with Prettier CLI on the provided index.d.ts example and compare the handling of prettier-ignore-start/end with single-line prettier-ignore. Trace the TypeScript formatting path and existing Markdown support; done means the B1/B2 region remains unchanged while C1 is formatted as shown.