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.

.eslintrc-hak.js

@@ -0,0 +1,37 @@
+module.exports = {
+    plugins: ["matrix-org"],
+    extends: ["plugin:matrix-org/javascript"],
+    parserOptions: {
+        ecmaVersion: 2021,
+        project: ["hak/tsconfig.json"],
+    },
+    env: {
+        es6: true,
+        node: true,
+        // we also have some browser code (ie. the preload script)
+        browser: true,
+    },
+    // NOTE: These rules are frozen and new rules should not be added here.
+    // New changes belong in https://github.com/matrix-org/eslint-plugin-matrix-org/
+    rules: {
+        "quotes": "off",
+        "indent": "off",
+        "prefer-promise-reject-errors": "off",
+        "no-async-promise-executor": "off",
+    },
+    overrides: [
+        {
+            files: ["hak/**/*.ts"],
+            extends: ["plugin:matrix-org/typescript"],
+            rules: {
+                // Things we do that break the ideal style
+                "prefer-promise-reject-errors": "off",
+                "quotes": "off",
+
+                "@typescript-eslint/no-explicit-any": "off",
+                // We're okay with assertion errors when we ask for them
+                "@typescript-eslint/no-non-null-assertion": "off",
+            },
+        },
+    ],
+};