Enable logging by default [Unity]

[dingsdax]

Update logs behavior to follow the same opt-in model as enableMetrics:

• Users are considered opted-in when:
  • They call the equivalent of Sentry.logger.*, or
  • They explicitly enable a logging integration.
• Change default: set enable logs to true.
• Audit all logging integrations to ensure:
  • No logs are emitted unless the integration is explicitly enabled.
• Update documentation:
  • Explain new default behavior of enableLogs.
  • Clarify requirement to explicitly enable logging integrations.

[linear-code]

UNITY-221

[bitsandfoxes]

This relies on getsentry/sentry-dotnet#5183 where the Unity SDK will inherit it automatically.