feat: Add debug_traceTransaction migration support for historical backend

[zjg555543]

Background

During the migration from Erigon to op-geth, the new node only stores data after the migration block, while historical data remains on the Erigon node. The debug_traceTransaction RPC method was not forwarding requests to the historical backend, causing failures when tracing transactions that occurred before the migration block.

Solution

Implemented hybrid routing for debug_traceTransaction following the LOCAL strategy pattern:

1. Added GetBackend() method in eth/tracers/api.go to allow precise transaction existence checks
2. Created XlayerHybridTracersAPI wrapper that:
   • Checks if a transaction exists locally using GetCanonicalTransaction
   • Handles indexing-in-progress scenarios by returning appropriate errors
   • Forwards to Erigon only when transaction is confirmed not found
   • Executes trace locally when transaction exists
3. Extended WrapAPIsForXlayer to handle debug namespace APIs