[earcut] Added types. (#22979)

* [earcut] Added types.
Double export matches source: https://github.com/mapbox/earcut/blob/master/src/earcut.js#L3-L4

* [earcut] Used interface, added flatten and deviation.

types/earcut/earcut-tests.ts

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+const a = earcut([10, 0, 0, 50, 60, 60, 70, 10]);
+// @example with a hole:
+const b = earcut([0, 0, 100, 0, 100, 100, 0, 100, 20, 20, 80, 20, 80, 80, 20, 80], [4]); // [3,0,4, 5,4,0, 3,4,7, 5,0,1, 2,3,7, 6,5,1, 2,7,6, 6,1,2]
+// @example with 3d coords:
+const c = earcut([10, 0, 1, 0, 50, 2, 60, 60, 3, 70, 10, 4], undefined, 3); // [1,0,3, 3,2,1]
+
+declare const vertices: number[];
+declare const holes: number[];
+declare const dimensions: number;
+const triangles = earcut(vertices, holes, dimensions);
+const deviation = earcut.deviation(vertices, holes, dimensions, triangles);
+
+const data = earcut.flatten([[[0, 0], [100, 0], [0, 100]], [[10, 10], [0, 10], [10, 0]]]);
+const triangles2 = earcut(data.vertices, data.holes, data.dimensions);
+
+declare const multiDimData: number[][][];
+const triangles3 = earcut(data.vertices, data.holes, data.dimensions);

types/earcut/index.d.ts

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+// Type definitions for earcut 2.1
+// Project: https://github.com/mapbox/earcut#readme
+// Definitions by: Adrian Leonhard <https://github.com/NaridaL>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// Duplicated export mirrors actual source: https://github.com/mapbox/earcut/blob/master/src/earcut.js#L3-L4
+
+interface EarcutStatic {
+	/**
+	 * Triangulate an outline.
+	 *
+	 * @param vertices A flat array of vertice coordinates like [x0,y0, x1,y1, x2,y2, ...].
+	 * @param holes An array of hole indices if any (e.g. [5, 8] for a 12-vertice input would mean one hole with vertices 5–7 and another with 8–11).
+	 * @param dimensions The number of coordinates per vertice in the input array (2 by default).
+	 * @return A flat array with each group of three numbers indexing a triangle in the `vertices` array.
+	 * @example earcut([10,0, 0,50, 60,60, 70,10]); // returns [1,0,3, 3,2,1]
+	 * @example with a hole: earcut([0,0, 100,0, 100,100, 0,100,  20,20, 80,20, 80,80, 20,80], [4]); // [3,0,4, 5,4,0, 3,4,7, 5,0,1, 2,3,7, 6,5,1, 2,7,6, 6,1,2]
+	 * @example with 3d coords: earcut([10,0,1, 0,50,2, 60,60,3, 70,10,4], null, 3); // [1,0,3, 3,2,1]
+	 */
+	(vertices: ArrayLike<number>, holes?: ArrayLike<number>, dimensions?: number): number[];
+
+	/**
+	 * Transforms multi-dimensional array (e.g. GeoJSON Polygon) into the format expected by earcut.
+	 * @example Transforming GeoJSON data.
+	 * 	const data = earcut.flatten(geojson.geometry.coordinates);
+	 * 	const triangles = earcut(data.vertices, data.holes, data.dimensions);
+	 * @example Transforming simple triangle with hole:
+	 * 	const data = earcut.flatten([[[0, 0], [100, 0], [0, 100]], [[10, 10], [0, 10], [10, 0]]]);
+	 * 	const triangles = earcut(data.vertices, data.holes, data.dimensions);
+	 * @param data Arrays of rings, with the first being the outline and the rest holes. A ring is an array points, each point being an array of numbers.
+	 */
+	flatten(data: ArrayLike<ArrayLike<ArrayLike<number>>>): { vertices: number[], holes: number[], dimensions: number };
+
+	/**
+	 * Returns the relative difference between the total area of triangles and the area of the input polygon. 0 means the triangulation is fully correct.
+	 * @param vertices same as earcut
+	 * @param holes same as earcut
+	 * @param dimensions same as earcut
+	 * @param triangles see return value of earcut
+	 * @example
+	 * 	const triangles = earcut(vertices, holes, dimensions);
+	 *  const deviation = earcut.deviation(vertices, holes, dimensions, triangles);
+	 */
+	deviation(vertices: ArrayLike<number>, holes: ArrayLike<number> | undefined, dimensions: number, triangles: ArrayLike<number>): number;
+
+	default: EarcutStatic;
+}
+declare const exports: EarcutStatic;
+export = exports;
+export as namespace earcut;

types/earcut/tsconfig.json

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+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictNullChecks": true,
+        "baseUrl": "../",
+        "typeRoots": [
+            "../"
+        ],
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true,
+        "strictFunctionTypes": true
+    },
+    "files": [
+        "index.d.ts",
+        "earcut-tests.ts"
+    ]
+}

types/earcut/tslint.json

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+{ "extends": "dtslint/dt.json" }