Announce supported schema ids in network before replication

[adzialocha]

This PR introduces our concept of "Announcements" (read more here: https://p2panda.org/specification/replication/#1-announcement).

There's a specification change involved: We need to give Announce messages their own message type. I've took 0 for them and changed the ones for SyncRequest, SyncDone and Entry as well. Related PR: p2panda/handbook#290

Closes #405

📋 Checklist

• Add tests that cover your changes
• Add this PR to the Unreleased section in CHANGELOG.md
• Link this PR to any issues it closes
• New files contain a SPDX license header

[codecov]

Codecov Report

Patch coverage: 88.08% and project coverage change: -0.19% ⚠️

Comparison is base (bf77be8) 92.35% compared to head (5dda823) 92.16%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #515      +/-   ##
==========================================
- Coverage   92.35%   92.16%   -0.19%     
==========================================
  Files          99      101       +2     
  Lines       15801    16079     +278     
==========================================
+ Hits        14593    14820     +227     
- Misses       1208     1259      +51     

Files Changed	Coverage Δ
aquadoggo/src/bus.rs	100.00% <ø> (ø)
aquadoggo/src/network/peers/handler.rs	73.07% <ø> (ø)
aquadoggo/src/network/peers/protocol.rs	100.00% <ø> (ø)
aquadoggo/src/network/service.rs	29.20% <0.00%> (+0.29%)	⬆️
aquadoggo/src/replication/errors.rs	50.00% <ø> (ø)
aquadoggo/src/replication/manager.rs	87.69% <ø> (ø)
aquadoggo/src/replication/ingest.rs	89.47% <14.28%> (-3.68%)	⬇️
aquadoggo/src/replication/service.rs	76.25% <77.77%> (-8.60%)	⬇️
aquadoggo/src/replication/message.rs	85.52% <93.33%> (+0.27%)	⬆️
aquadoggo/src/schema/schema_provider.rs	93.57% <94.73%> (-0.37%)	⬇️
... and 4 more

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

[adzialocha]

I don't feel like adding more tests to this, we have e2e tests checking against successful replication which still succeeded and I've extended our replication service "lifetime" test to deal with announcement messages. Think that should be sufficient?

[sandreae]

I had a couple of comments, only about naming. Except for that, all looking really good!