Eslint (#998)

## Description:

Enable a few eslint rules:
- `@typescript-eslint/no-empty-object-type`
- `@typescript-eslint/no-require-imports`
- `no-useless-escape`

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

---------

Co-authored-by: Scott Anderson <scottanderson@users.noreply.github.com>

src/core/validations/username.ts

@@ -22,7 +22,7 @@ const matcher = new RegExpMatcher({
 export const MIN_USERNAME_LENGTH = 3;
 export const MAX_USERNAME_LENGTH = 27;
 
-const validPattern = /^[a-zA-Z0-9_\[\] 🐈🍀üÜ]+$/u;
+const validPattern = /^[a-zA-Z0-9_[\] 🐈🍀üÜ]+$/u;
 
 const shadowNames = [
   "NicePeopleOnly",