Bluetooth: Host: Add host support for Advertising Coding Selection

Extends the API for Advertising Coding Selection.

The API is extended to set the Advertising Coding Selection
(Host Support) bit. With this feature, the primary and
secondary PHY can now explicitly report S=2 or S=8 coding
in the extended advertising report. Previously, the report
only indicated LE Coded regardless of whether S=2 or S=8
data coding was used. The API now sets the host support bit
and ensures that the advertising PHY coding scheme is
conveyed to the application via the scan callback.

The support is enabled by CONFIG_BT_EXT_ADV_CODING_SELECTION,
and requires a controller that selects
CONFIG_BT_CTLR_ADV_EXT_CODING_SELECTION_SUPPORT.

Signed-off-by: Thomas Deppe <thomas.deppe@nordicsemi.no>