feat(ruby): Add Nested path filtering support with dot notation

[kylewelsby]

🧰 Changes

This PR adds the abuility to filter nested objects using dot notation (e.g. user.password, payment.card.number). The feature improves API logging security by allowing precise filtering of nested sensitive data.

Key changes:

• Added PathProcessor module to handling dot notation paths
• Support for array path notation (users[].password)
• Case-insensitive path matching
• Maintains string length in redacted values
• Adds support for both reject and allow-only filtering

Example usage:

# Reject specific nested fields
filter = Readme::Filter.for(reject: ['user.password', 'payment.card.number'])
filter.filter({
  user: { 
    name: 'John',
    password: 'secret'
  }
})
# => { user: { name: 'John', password: '[REDACTED 6]' } }

# Allow only specific nested fields
filter = Readme::Filter.for(allow_only: ['user.name'])

🧬 QA & Testing