bluetooth: host: Add support for extended feature set feature

This commit adds support for the extended feature set
feature. This includes:
- hci boilerplate
- kconfigs, including one for a max local feature page
- reading remote features is done by a command and callback
- this is not linked into the auto feature request on
connection as this procedure can take quite a few connection
events, and we do not want to delay the user
- added the commands to the bt shell

Signed-off-by: Sean Madigan <sean.madigan@nordicsemi.no>