Workaround for H4 HCI stream corruption during LE scans

Sometimes, during result-heavy LE scans, the UART byte stream can become
corrupted, leading to assertions caused by mis-interpreting the bytes
following the corruption.

This workaround looks for tell-tale signs of a BLE event and attempts to
skip the correct amount of bytes in the stream to re-synchronize onto a
packet boundary.

Bug: 23934838
Change-Id: Ifadaecf8077cb1defc7134c59c97302fca660f81