Reland "[Nearby Connections] MVP for StartAdvertising on BLE v2"

This is a reland of commit 7b9b892c

Failing builder: https://ci.chromium.org/ui/p/chromium/builders/ci/Linux%20ChromiumOS%20MSan%20Tests/42040/overview

Failure reason: `Uninitialized value was created by an allocation of 'advertising_data' in the stack frame`

Original change's description:
> [Nearby Connections] MVP for StartAdvertising on BLE v2
>
> Implements the MVP for StartAdvertising on BLE v2. This function works
> properly, and was tested with Fast, Legacy, and Extended advertisements.
>
> Test: Manual testing and unit tests.
> Bug: b/320554697
> Bug: b/330759317
> Change-Id: I94f473a6f4ed95ee312546ac42f8f33e06ecc8f4
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5347437


> Reviewed-by: Ryan Hansberry <hansberry@chromium.org>
> Commit-Queue: Daniel Classon <dclasson@google.com>
> Reviewed-by: Jack Shira <jackshira@google.com>
> Cr-Commit-Position: refs/heads/main@{#1277169}

Bug: b/320554697
Bug: b/330759317
Test: `testing/xvfb.py out/Default/unit_tests --gtest_filter=*BleV2MediumTest.TestAdvertising* --asan=0 --lsan=0 --msan=1 --tsan=0`
Change-Id: I7fe55d82f126fa61470b7695455fa063e28ced09
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5392541


Reviewed-by: Jack Shira <jackshira@google.com>
Commit-Queue: Daniel Classon <dclasson@google.com>
Reviewed-by: Ryan Hansberry <hansberry@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1278431}