Protected Audiences: Wire up TrustedSignalsCache to BidderWorket code.

This CL makes AuctionWorkletServiceImpl pass the TrustedSignalsCache,
if it has one, to BidderWorklets it creates, and makes the
BidderWorklets use them to fetch signals when requests have a
`trusted_signals_cache_key`.

Bug: 333445540
Change-Id: I72034412b3b9e8d0082fa7b0c5eff902c410ad2d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5909838
Reviewed-by: Russ Hamilton <behamilton@google.com>
Commit-Queue: mmenke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1368324}