Add EIP-7928 (Block-Level Access Lists) Metrics

## Goal
Discuss and propose metrics needed to monitor the implementation of [EIP-7928](https://eips.ethereum.org/EIPS/eip-7928) (Block-Level Access Lists). These metrics will help track BAL construction, validation, performance, and content characteristics.

## Proposed Metrics

### Block-Level Metrics
- `execution_block_total_size_bytes` (gauge) - Total size of the block including BAL in bytes
- `execution_block_execution_time_seconds` (histogram) - Total time taken to execute the block

### BAL Size and Structure
- `execution_block_access_list_size_bytes` (gauge) - Size of the BAL in bytes for the current block

### BAL Validation Metrics
- `execution_block_access_lists_valid_total` (counter) - Total number of blocks with valid BALs
- `execution_block_access_lists_invalid_total` (counter) - Total number of blocks with invalid BALs
- `execution_block_access_list_validation_time_seconds` (histogram) - Time taken to validate the BAL against actual execution

### BAL Content Metrics
- `execution_block_access_list_account_changes` (gauge) - Number of account changes in the BAL
- `execution_block_access_list_storage_changes` (gauge) - Number of storage changes in the BAL
- `execution_block_access_list_balance_changes` (gauge) - Number of balance changes in the BAL
- `execution_block_access_list_nonce_changes` (gauge) - Number of nonce changes in the BAL
- `execution_block_access_list_code_changes` (gauge) - Number of code changes in the BAL

## Discussion Points
- Are these metrics sufficient for monitoring BAL implementation?
- Should any metrics use different types (e.g., histograms instead of counters for content metrics)?
- Are there additional metrics needed for parallelization monitoring or performance analysis?