RootCanal: Fragment large advertising reports

LE Extended advertising lets host stacks define
advertising data as large as 1650 bytes.
Extended advertising reports can generally not be sent as one
HCI event and need to be fragmented.

Implement extended scanning test LL/DDI/SCN/BV-19-C
for validation.

Bug: 271910328
Test: atest rootcanal_ll_test
Change-Id: I2f7ea668524078a8241994814ac863ab3efc9b6f