Separate linting and compiling src+test, scripts and hak

Inspired by the failure of https://github.com/vector-im/element-desktop/pull/529
to lint our code with the @typescript-eslint/no-base-to-string rule
turned on, I found we needed to add a parserOptions.project to our
.eslintrc.js, pointing to the tsconfig.json.

This led to more fixes, because we have 3 tsconfig.json files for
src+test, scripts and hak and the single eslintrc was complaining that
it could see more files than the tsconfig file knew about.

So, I think the right split is to have one eslintrc file and one
tsconfig for each of the three projects.

tsconfig.json

@@ -12,5 +12,5 @@
         "types": ["jest", "node"],
         "strict": true
     },
-    "include": ["./src/**/*.ts", "./tests/**/*.ts"]
+    "include": ["./src/**/*.ts", "./test/**/*.ts"]
 }