fix: Add Nested quantization check

[jeffkinnison]

Using LLMEncoder with 8-bit quantization can lead to the same error addressed by #3606. This happens because the quantization check does not account for quantization config nested in the encoder block. This adds a utility for retrieving all quantization information from a config, including accounting for multiple quantized encoders, and updates the trainer to use this utility.

[github-actions]

Unit Test Results

  6 files  ±0    6 suites  ±0   14m 14s ⏱️ -2s
12 tests ±0    9 ✔️ ±0    3 💤 ±0  0 ❌ ±0 
60 runs  ±0  42 ✔️ ±0  18 💤 ±0  0 ❌ ±0 

Results for commit 318aa19. ± Comparison against base commit 9bb89c6.

♻️ This comment has been updated with latest results.