feat: adding option to set initial and max memory

[signorecello]

This PR adds an object with type BackendOptions, allowing to set number of threads and the memory to be allocated.

The initial motivation was to allow for bb.js to generate proofs on phones, as some would immediately kill the worker if the default value for maximum was used (2 ** 16, about 4gb).

Turned it into an object so it closely matches the implementation in @noir-lang/backend_barretenberg

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 cc515dab 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	222,972	868,268	3,449,492
l1_rollup_execution_gas	842,059	3,595,376	22,204,861
l2_block_processing_time_in_ms	2,212 (+1%)	8,552 (+1%)	35,483 (+1%)
note_successful_decrypting_time_in_ms	350 (+3%)	1,072 (+4%)	3,967 (+5%)
note_trial_decrypting_time_in_ms	62.2 (+25%)	37.6 (-6%)	140
l2_block_building_time_in_ms	20,259	80,642	323,491
l2_block_rollup_simulation_time_in_ms	16,691	66,485	266,907
l2_block_public_tx_process_time_in_ms	3,534	14,089	56,337

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	24,342	47,501
note_history_successful_decrypting_time_in_ms	2,510	5,200 (+2%)
note_history_trial_decrypting_time_in_ms	79.0 (+6%)	145 (-1%)
node_database_size_in_bytes	3,627,997	3,920,633
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 (+1%)	43,109	20,441
private-kernel-ordering	115 (+1%)	25,833	9,689
base-rollup	2,970	667,692	873
root-rollup	88.9 (+3%)	4,072	881
private-kernel-inner	261	64,516	20,441
public-kernel-private-input	172 (+1%)	25,203	20,441
public-kernel-non-first-iteration	171 (+1%)	25,245	20,441
merge-rollup	10.8 (+1%)	2,592	873

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	26,359