rust: Rust sanitized snapshots variations

This adds support for correctly handling Rust sanitized snapshots,
ensuring they only have one variation.

The presence of multiple variations were causing build failures
when a rust_fuzz module for host was defined and a snapshot
build was requested.

This also sets -Z link-native-libraries=no on host modules
(in addition to device modules) to avoid emitting extra linkage
flags due to link attributes.

Bug: 282897366
Test: SOONG_SDK_SNAPSHOT_USE_SRCJAR=true m
Change-Id: Idf980c29145f11c530ad635a4eb5b01a1730ac24