RUM-12495: Support trace sampling based on Session Id#169
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What does this PR do?
Previously, each HTTP request through DdUrlTransfer made an independent random sampling decision, so two requests in the same session could get different decisions.
This change makes trace sampling deterministic per-session: the last 48 bits of the session UUID are used as a seed for the same Knuth multiplicative hash (× 1111111111111111111) used by the Android and iOS SDKs. Requests in the same session now always receive the same sampling decision, consistent with backend expectations.
When no active session is present, the previous random fallback is preserved.
Note on implementation: BrightScript's LongInteger * does not wrap on 64-bit overflow — it uses double arithmetic for large products. The Knuth multiplication is therefore implemented via 16-bit chunk decomposition to stay within safe integer range, then assembled as a double for the threshold comparison.
Review checklist (to be filled by reviewers)