Bluetooth: Add link mode config in blueship manager

Add a way to configure the link mode so that tests can force central or
peripheral role.

BUG=b:424465326
TEST=Run BeTo role_conflict test and confirm mode in btsnoop log

Change-Id: I25666f6cab03b8099836ebd5f1d8e278e17e2ace
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/chameleon/+/6689099
Commit-Queue: Manish Mandlik <[email protected]>
Reviewed-by: Yun-hao Chung <[email protected]>
Tested-by: Manish Mandlik <[email protected]>
5 files changed