Add BLE Support for nRF52832

[lonesometraveler]

This pull request introduces BLE support for the nrf52832 microcontroller, resolving issue #7.

Changes:

• Added support for nRF52832.
• Introduced new features named nrf52840 and nrf52832. These features enable specific configurations tailored to each microcontroller.

As a result of these changes, modifications have been made in Cargo.toml under boards/nrf52840_ble:

[dependencies]
rmk = { version = "0.1.5", path = "../../rmk", features = [
    "ble",
    "nrf52840",
    "eeprom",
    "col2row",
] }

Testing:

• Verified the firmware's functionality on nRF52832 hardware.

[HaoboGu]

LGTM, thanks!