chore(docs): Update token bridge tutorial

[critesjosh]

This PR adds source code references to code that was previously hard coded. It also adds a couple of functions that are in the implementation but were not referenced in the tutorial.

• removes references to the utils.nr file that is no longer used in the implementation in noir-contracts.
• Adds the FORK_URL and FORK_BLOCK_NUMBER env vars to the sandbox reference page

Checklist:

Remove the checklist to signal you've completed it. Enable auto-merge if the PR is ready to merge.

• If the pull request requires a cryptography review (e.g. cryptographic algorithm implementations) I have added the 'crypto' tag.
• I have reviewed my diff in github, line by line and removed unexpected formatting changes, testing logs, or commented-out code.
• Every change is related to the PR description.
• I have linked this pull request to relevant issues (if any exist).

[AztecBot]

Benchmark results

No metrics with a significant change found.

Detailed results

All benchmarks are run on txs on the Benchmarking contract on the repository. Each tx consists of a batch call to create_note and increment_balance, which guarantees that each tx has a private call, a nested private call, a public call, and a nested public call, as well as an emitted private note, an unencrypted log, and public storage read and write.

This benchmark source data is available in JSON format on S3 here.

Values are compared against data from master at commit 5c6c2caf and shown if the difference exceeds 1%.

L2 block published to L1

Each column represents the number of txs on an L2 block published to L1.

Metric	8 txs	32 txs	128 txs
l1_rollup_calldata_size_in_bytes	45,444	179,588	716,132
l1_rollup_calldata_gas	222,924	868,232	3,449,696
l1_rollup_execution_gas	842,011	3,595,340	22,205,358
l2_block_processing_time_in_ms	1,341 (+1%)	5,285 (+1%)	21,268 (+1%)
note_successful_decrypting_time_in_ms	346 (+1%)	1,053	3,837 (+1%)
note_trial_decrypting_time_in_ms	57.0 (+6%)	32.3 (-14%)	138 (+3%)
l2_block_building_time_in_ms	13,806 (+2%)	53,910	217,973
l2_block_rollup_simulation_time_in_ms	10,235 (+2%)	39,831	161,279
l2_block_public_tx_process_time_in_ms	3,541	14,013	56,459 (+1%)

L2 chain processing

Each column represents the number of blocks on the L2 chain where each block has 16 txs.

Metric	5 blocks	10 blocks
node_history_sync_time_in_ms	15,695 (-2%)	29,935
note_history_successful_decrypting_time_in_ms	2,724 (+4%)	5,074 (+5%)
note_history_trial_decrypting_time_in_ms	153 (+39%)	156 (-23%)
node_database_size_in_bytes	3,910,569	4,258,465 (+1%)
pxe_database_size_in_bytes	29,940	59,499

Circuits stats

Stats on running time and I/O sizes collected for every circuit run across all benchmarks.

Circuit	circuit_simulation_time_in_ms	circuit_input_size_in_bytes	circuit_output_size_in_bytes
private-kernel-init	200	43,109	20,441
private-kernel-ordering	115	25,833	9,689
base-rollup	2,065	244,144	881
root-rollup	82.4 (-3%)	4,088	889
private-kernel-inner	261	64,516	20,441
public-kernel-private-input	172	25,203	20,441
public-kernel-non-first-iteration	171	25,245	20,441
merge-rollup	9.73 (-2%)	2,608	881

Miscellaneous

Transaction sizes based on how many contracts are deployed in the tx.

Metric	0 deployed contracts	1 deployed contracts
tx_size_in_bytes	10,323	26,309