PLA-2317: Fix block re-processing crashes in EventProcessor, ExtrinsicProcessor, and TokenCreated

[pawell67]

ExtrinsicProcessor/EventProcessor:

• Guard against string values from DB longText columns for block.events and block.extrinsics (is_array check instead of null-coalescing)
• Filter null events before accessing extrinsicIndex property to prevent "Attempt to read property on null" errors in saveExtrinsicEvents and updateTransaction

TokenCreated:

• Use firstOrCreate instead of create to prevent UniqueConstraintViolationException when re-processing blocks where the token already exists from a later block's ingestion