feat: allow StreamHanlder to broadcast StreamMessages

[guy-starkware]

This adds the other communications direction, e.g., from the Consensus into the network.

The StreamHandler gets a receiver of receivers (well, actually it gets a tuple with stream_id and a receiver).
Each new receiver corresponds to a new stream_id (in the Consensus case it would be a new height).

Then, messages that come in the form of generic T (can be any protobuf-able message) are packaged into StreamMessage and sent out to the network.

When the Fin message comes, the receiver channel is dropped.

---

This change is 

[codecov]

Codecov Report

Attention: Patch coverage is 88.23529% with 8 lines in your changes missing coverage. Please review.

Project coverage is 28.70%. Comparing base (b0cfe82) to head (4dd6edc).
Report is 302 commits behind head on main.

Files with missing lines	Patch %	Lines
...sequencing/papyrus_consensus/src/stream_handler.rs	89.39%	3 Missing and 4 partials ⚠️
crates/papyrus_network_types/src/network_types.rs	0.00%	1 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (b0cfe82) and HEAD (4dd6edc). Click for more details.

HEAD has 2 uploads less than BASE

Flag	BASE (b0cfe82)	HEAD (4dd6edc)
	3	1

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1253       +/-   ##
===========================================
- Coverage   74.18%   28.70%   -45.48%     
===========================================
  Files         359       68      -291     
  Lines       36240     9077    -27163     
  Branches    36240     9077    -27163     
===========================================
- Hits        26886     2606    -24280     
+ Misses       7220     6372      -848     
+ Partials     2134       99     -2035     

Flag	Coverage Δ
	?

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

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.