Remove msg-sending IO from Connection protocol

[Patrik-Stas]

Remove message sending IO from Connection protocol state machines

Changes

Inviter

• remove Responded state
• in state InviterConnection<Requested>:
  • remove method send_response
  • add method get_connection_response_msg

Invitee

• in state InviteeConnection<Responded>

  • remove method send_ack
  • add method get_ack

• in state InviteeConnection<Invited>

  • remove method send_request
  • add method prepare_request

• in state InviteeConnection<Requested>

  • change return type of handle_response from InviteeConnection<Responded> to InviteeConnection<Completed>

• remove state Responded

  • previously the state sequence was like this:

  Requested ----(handle_response)----> Responded ----(send_ack)----> Completed
  

  • now tracking whether ack has been sent or not became responsibility of the state machine consumer. The sequence is now following:

  Requested ----(handle_response)----> Completed
  

Breaking Changes

• Removal of Invitee's state Responded. Existing state machines in such state won't be deserializable anymore.

[codecov-commenter]

Codecov Report

Merging #937 (11cbec1) into main (f8aaadc) will increase coverage by 0.11%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #937      +/-   ##
==========================================
+ Coverage   39.35%   39.46%   +0.11%     
==========================================
  Files         417      415       -2     
  Lines       28986    28906      -80     
  Branches     6185     6174      -11     
==========================================
+ Hits        11407    11408       +1     
+ Misses      14236    14155      -81     
  Partials     3343     3343              

Flag	Coverage Δ
unittests-aries-vcx	39.46% <0.00%> (+0.11%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
...cx/src/protocols/connection/generic/conversions.rs	0.00% <ø> (ø)
aries_vcx/src/protocols/connection/generic/mod.rs	0.00% <0.00%> (ø)
...vcx/src/protocols/connection/generic/thin_state.rs	0.00% <ø> (ø)
aries_vcx/src/protocols/connection/invitee/mod.rs	0.00% <0.00%> (ø)
...c/protocols/connection/invitee/states/requested.rs	0.00% <0.00%> (ø)
aries_vcx/src/protocols/connection/inviter/mod.rs	0.00% <0.00%> (ø)
aries_vcx/src/protocols/connection/serializable.rs	0.00% <ø> (ø)

... and 3 files with indirect coverage changes