Convert perform_pair_setup_part* to be state machines

[Jc2k]

As promised here is the other half of #161. The perform_pair_setup_part* functions are now 'pure' state machines - they don't do the IO themselves, and this means we can reuse them with the async client in #154. When this lands i will be able to completely rm homekit/aio/controller/ip/crypto.py from that branch.

(And this does eliminate create_ble_pair_verify_write again).

[jlusiardi]

so we do not have separate functions for create_ble_pair_verify_write and create_ble_pair_setup_write anymore, can we find a better name? perhaps create_characteristic_write_function?

[Jc2k]

I think we can actually factor out the need for the create_ part entirely really, but i didn't want to over complicate this PR.

Now that we aren't passing it into the state machine we don't need to capture the scope. So it could just be a generic write helper like (pseudo-code, won't work as is):

def write_hap_param_value(char, iid, request, expected):
    pass

...

def setup_session():
    char, iid = find_char_by_type(PAIR_VERIFY)
    state_machine = ...
    while True:
        response = write_hap_param_value(char, iid, request, expected)
        request, expected = state_machine.send(response)

[jlusiardi]

I will try to perform some tests with a real hardware!

[jlusiardi]

Done and lgtm

[Jc2k]

Wahhooooo