[TS] Force explicit override & property access (#1006)

Enables TypeScript rules that improve code legibility.

- Requires `override` keyword
- Prevent indexed properties from being accessed with dot notation

```ts
const obj: Record<string, unknown> = {}

// Prefer
obj["property"]

// Over
obj.property
```

tsconfig.json

@@ -19,6 +19,8 @@
     "noUnusedParameters": false,
     "noFallthroughCasesInSwitch": true,
     "downlevelIteration": true,
+    "noImplicitOverride": true,
+    "noPropertyAccessFromIndexSignature": true,
 
     /* AllowJs during migration phase */
     "allowJs": true,