feat(lobster): include upstream system requirements in dependable_element traceability

[simon-d-bmw]

Problem

When a feature_requirements() target has deps on assumed_system_requirements(), the upstream requirement lobster files are not included in the dependable_element lobster config or report. This means derived_from links from feature requirements to system-level requirements silently produce unresolved references in the lobster coverage report.

Proposed Change

providers.bzl — add upstream_srcs field to FeatureRequirementsInfo:

FeatureRequirementsInfo = provider(
    fields = {
        "srcs": "...",
        "upstream_srcs": "Depset of .lobster files from upstream req deps (e.g. assumed system requirements).",
        "name": "...",
    },
)

private/requirements.bzl — populate upstream_srcs when building FeatureRequirementsInfo: collect AssumedSystemRequirementsInfo.srcs from all deps and include as transitive depset.

private/component.bzl — propagate upstream_srcs alongside srcs when collecting feature requirement lobster files in _component_impl.

private/dependable_element.bzl — in _dependable_element_index_impl:

• collect upstream_req_list from FeatureRequirementsInfo.upstream_srcs
• pass as {UPSTREAM_REQ_SOURCES} substitution to lobster config template
• include in all_lobster_inputs

lobster/config/lobster_de.conf.tpl — add section:

requirements "System Requirements" {
{UPSTREAM_REQ_SOURCES}
}

Motivation

Downstream projects that wire swe-as-code assumed_system_requirements into their dependable element currently get lobster warnings for every derived_from link pointing at a system-level requirement. This change makes the traceability chain complete without requiring system requirement TRLC files to be duplicated inside the downstream project.