Migrate helpers.rs to use protocol's from_package() methods

[Keinberger]

The helpers in integration/src/helpers.rs manually reimplement functionality that now exists natively in miden-protocol on the next branch:

• account_component_from_package() manually extracts metadata sections and calls AccountComponent::new() with raw storage slots. This is replaced by AccountComponent::from_package(&package, &init_storage_data) which handles metadata extraction and storage initialization internally.
• create_note_from_package() manually calls package.unwrap_program() and NoteScript::from_parts(). This is replaced by NoteScript::from_package(&package) which uses the @note_script attribute to find the entrypoint.
• Note assembly can be simplified using NoteBuilder::package() from miden-standards::testing.

Once we upgrade to v0.14/v0.15 protocol dependencies, we should replace the local helpers with these protocol methods. This will also simplify AccountCreationConfig (can drop storage_slots and supported_types fields since from_package() handles those via package metadata).

Related: protocol#2689