Pull the whole "Testing" documentation section up to the top level

[mhalbritter]

Please also consider pulling the whole "Testing" section up to the top level so it shows up in the left nav.

Originally posted by @dsyer in #33975 (comment)

[scottfrederick]

I agree we could use more fine-tuning of the organization of the docs in this area. In the latest snapshot docs, we have:

• 7.9. Testing
  • 7.9.1. Test Scope Dependencies
  • 7.9.2. Testing Spring Applications
  • 7.9.3. Testing Spring Boot Applications
  • 7.9.4. Testcontainers
  • 7.9.5. Test Utilities
• 7.10. Docker Compose Support
• 7.11. Testcontainers Support

Testcontainers appears twice, but it's not clear what the differences between the two sections are (integration tests vs development-time services).

7.10 Docker Compose Support and 7.11 Testcontainers Support talk about development-time services, so maybe those could be under a common heading to make that more clear.

[mhalbritter]

7.10 Docker Compose Support and 7.11 Testcontainers Support talk about development-time services, so maybe those could be under a common heading to make that more clear.

I think that's a good idea.