Use new types for BLE address and Gap

[LDong-Arm]

In https://github.com/ARMmbed/mbed-os/pull/12730 we have removed legacy address-related types (BLEProtocol:: namespace) in favour of new once in ble:: namespace. This PR updates examples so they will continue to work the latest Mbed OS.

Changes:

• BLEProtocol::AddressType_t -> ble::own_address_type_t
• BLEProtocol::AddressBytes_t -> ble::address_t

Additionally, in #289 we fixed types for Gap, but it got reverted because it contains a typo fix which hasn't landed in mbed-os repo yet. This PR also brings that back.

• Gap::Phy_t -> ble::phy_t
• Gap::Handle_t -> ble::connection_handle_t
• GapAdvertisingData::LE_GENERAL_DISCOVERABLE -> ble::adv_data_flags_t(value).getGeneralDiscoverable()
• Gap::CentralPrivacyConfiguration_t -> ble::central_privacy_configuration_t (Note: currently spelt "privay" in mbed-os, corrected by https://github.com/ARMmbed/mbed-os/pull/12730)

Note: This change is in conjunction with https://github.com/ARMmbed/mbed-os/pull/12730 - they have to be merged roughly at the same time.

[LDong-Arm]

@ARMmbed/mbed-os-pan @pan- @evedon This is another (and should be the final) round of BLE examples update. It needs to get in at the same time as ARMmbed/mbed-os#12730 in mbed-os due to an API change.