support softdevice api v7

[sharowyeh]

1. Since nrf5 SDK v17.1 (which connectivity supports sd_api_v7.2) has been released a few years ago, if any possibility of upgrading this connectivity host app to the latest sd_api_v7.
2. Nordic noted that nrf5 SDK has been in maintenance without any further upgrade, it should be considered migrating to ncs(connect SDK).

[sharowyeh]

• based on nrf52840 compatibility matrix for sdk and softdevice
  can focus on s140 SDS(softdevice spec) v2.1, compares to currently following v1.3 from softdevice v6.1.1 by SDK v15.3
• so far NRF_SD_BLE_API_VERSION > 7 is only founded in softdevice s122 ble_gap.h from SDK v17.1.0, the change is interval/window ble_scan_param_t from unit to us