test: modernize mocha config (#356)

Author: JustinBeckwith

packages/google-cloud-language/.mocharc.json

@@ -0,0 +1,5 @@
+{
+  "enable-source-maps": true,
+  "throw-deprecation": true,
+  "timeout": 10000
+}

packages/google-cloud-language/package.json

@@ -56,15 +56,13 @@
     "eslint-plugin-node": "^11.0.0",
     "eslint-plugin-prettier": "^3.0.0",
     "gts": "^1.0.0",
-    "intelli-espower-loader": "^1.0.1",
     "jsdoc": "^3.5.5",
     "jsdoc-fresh": "^1.0.1",
     "jsdoc-region-tag": "^1.0.2",
     "linkinator": "^1.5.0",
     "mocha": "^7.0.0",
     "null-loader": "^3.0.0",
     "pack-n-play": "^1.0.0-2",
-    "power-assert": "^1.6.0",
     "prettier": "^1.11.1",
     "ts-loader": "^6.2.1",
     "typescript": "^3.7.0",