feat: introducing rate-limiting on queries, mutations and most of the REST endpoints (HBE-111) (#46)

* feat: rate-limiting guard added and configured in app module

* feat: rate-limit annotation added in controllers and resolvers (query, mutation, not subscription)

* docs: added comments

packages/hoppscotch-backend/.env.example

@@ -5,6 +5,10 @@ DATABASE_URL=postgresql://postgres:testpass@dev-db:5432/hoppscotch
 MAILER_SMTP_URL="smtps://user@domain.com:pass@smtp.domain.com"
 MAILER_ADDRESS_FROM='"From Name Here" <from@example.com>'
 
+# Rate Limit Config
+RATE_LIMIT_TTL=60 # In seconds
+RATE_LIMIT_MAX=100 # Max requests per IP
+
 # Auth Tokens Config
 JWT_SECRET='add some secret here'
 TOKEN_SALT_COMPLEXITY=10