feat: Add new tile accessor to get at tile props (#445)

Based on this conversation excaliburjs/Excalibur#2673

We want a convenient way to get at custom tile properties!

```typescript

// Grab tiles by worldspace point and the named layer
const tile = map.getTileByPoint('Ground', evt.worldPos);
// or by coordinate
const tile = map.getTileByCoordiante('Ground, 10, 100);

console.log('tile', tile);
console.log('id', tile?.id);
console.log('tile props', tile?.properties);
```

example/game.ts

@@ -86,22 +86,10 @@ const start = (mapFile: string) => {
    game.start(loader).then(() => {
 
       game.input.pointers.primary.on('down', evt => {
-         // ex TileMap data structure by name
-         const tilemap = map.getTileMapLayers().filter(tm => tm.name === 'Ground')[0];
-         const tile = tilemap.getTileByPoint(evt.worldPos);
-         const tileIndex = tilemap.tiles.indexOf(tile);
-
-         // Tiled data
-         // gid can be found by looking up the original data, locate layer by name
-         const tiledLayer = map.data.getTileLayerByName('Ground');
-         const tileGid = tiledLayer.data[tileIndex];
-
-         // tileset properties
-         const tiledTileset = map.getTilesetForTile(tileGid);
-         // odd quirk of Tiled's data the gid's here are off by 1 from the data array :/
-         const tiledTile = tiledTileset.tiles.find(t => t.id === (tileGid - 1));
-         console.log('gid', tileGid);
-         console.log('tile props', tiledTile?.properties);
+         const tile = map.getTileByPoint('Ground', evt.worldPos);
+         console.log('tile', tile);
+         console.log('id', tile?.id);
+         console.log('tile props', tile?.properties);
       });
 
       player.pos = ex.vec(100, 100);

src/tiled-map-resource.ts

@@ -25,14 +25,15 @@ import {
    IsometricMap,
    IsometricEntityComponent,
    Animation,
-   ParallaxComponent
+   ParallaxComponent,
+   Tile
 } from 'excalibur';
 import { ExcaliburData } from './tiled-types';
 import { RawTiledTileset } from "./raw-tiled-tileset";
 import { RawTiledLayer } from "./raw-tiled-layer";
 import { RawTiledMap } from "./raw-tiled-map";
 import { TiledMap } from './tiled-map-parser';
-import { parseExternalJson, parseExternalTsx, TiledTileset } from './tiled-tileset';
+import { parseExternalJson, parseExternalTsx, TiledTileset, TiledTilesetTile } from './tiled-tileset';
 import { getCanonicalGid, isFlippedDiagonally, isFlippedHorizontally, isFlippedVertically } from './tiled-layer';
 import { getProperty, TiledEntity } from './tiled-entity';
 import { TiledObjectComponent } from './tiled-object-component';
@@ -705,4 +706,48 @@ export class TiledMapResource implements Loadable<TiledMap> {
       }
       return [];
    }
+
+   private _lookupTile(tilemap: TileMap, tile: Tile, layerName: string) {
+      const tileIndex = tilemap.tiles.indexOf(tile); // both ex and tiled share the same index
+
+      // Tiled data
+      // gid can be found by looking up the original data, locate layer by name
+      const tiledLayer = this.data.getTileLayerByName(layerName);
+      const tileGid = getCanonicalGid(tiledLayer.data[tileIndex]);
+
+      // Tiled tileset properties
+      const tiledTileset = this.getTilesetForTile(tileGid);
+      // odd quirk of Tiled's data the gid's here are off by 1 from the data array :/
+      const tiledTile = tiledTileset.tiles.find(t => t.id === (tileGid - 1));
+      if (!tiledTile) {
+         return {
+            id: tileGid - 1,
+            tileset: tiledTileset,
+            properties: {}
+         } as TiledTilesetTile
+      }
+      return tiledTile;
+   }
+
+   public getTileByPoint(layerName: string, worldPos: Vector): TiledTilesetTile | null {
+      // ex TileMap data structure by name
+      const tilemap = this.getTileMapLayers().find(tm => tm.name === layerName);
+      if (tilemap) {
+
+         const tile = tilemap.getTileByPoint(worldPos);
+         return this._lookupTile(tilemap, tile, layerName);
+      }
+      return null;
+   }
+
+   public getTileByCoordinate(layerName: string, x: number, y: number): TiledTilesetTile | null {
+      // ex TileMap data structure by name
+      const tilemap = this.getTileMapLayers().find(tm => tm.name === layerName);
+      if (tilemap) {
+
+         const tile = tilemap.getTile(x, y);
+         return this._lookupTile(tilemap, tile, layerName);
+      }
+      return null;
+   }
 }