roll: pigweed, pw_toolchain: pw_bluetooth_sapphire: Refactor LowEnergyScanResult to its own class

The LowEnergyScanResult class was previously a struct with all public
members used to track the elements related to a scan result. A bit
awkwardly, the advertising data and scan response data related to the
scan result was stored in LowEnergyScanner::PendingScanResult.

This change updates LowEnergyScanResult to store the advertising data
and scan response data within itself. To present a better API to users,
and to prevent accidental modification, LowEnergyScanResult is now a
class with getters and setters instead of a struct with all public
members.

Since LowEnergyScanResult stores the advertising data and scan response
data itself, we can also modify the
LowEnergyScanner::Delegate::OnPeerFound API to simply take the
LowEnergyScanResult alone instead of also taking in the data as a
separate argument. We only did that because the data was stored
separately.

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/987909
GitOrigin-RevId: 9b3b47f13c3c8b41c4a00fe4a2d2a2688b9a807c
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/218975
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https://pigweed.googlesource.com/pigweed/pigweed
pigweed, pw_toolchain Rolled-Commits: 5c3289c29896ea2..f219e65ac4075ab
Roller-URL: https://ci.chromium.org/b/8743458863914510497
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Change-Id: I897746352b081e238dce4da5b66828c7c86fd8c8
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/quickstart/bazel/+/220031
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