Add LayoutLM to NormalizedConfigManager

[BortnikMaxim]

What does this PR do?

Registers LayoutLM with NormalizedConfigManager using NormalizedTextConfig, and removes it from the unsupported-model note.

LayoutLMConfig exposes the standard hidden_size, num_attention_heads, and num_hidden_layers attributes. The new offline regression test verifies that all three are normalized correctly.

Addresses the LayoutLM subtask in #351.

Validation

• Targeted regression test: 1 passed
• Black check on changed files: passed
• Ruff check on changed files: passed
• Python compile check on changed files: passed
• git diff --check: passed