chore: make some structs to be public

[yangby-cryptape]

What this PR does / why we need it?

This PR is useful for creating network tools on Axon chain. For example: count all nodes, p2p protocol fuzz tester.

Commits

• chore: make some structs to be public
• chore: move constants to a lightweight crate To avoid compile RocksDB when users just want to refer the gossip endpoints.

What is the impact of this PR?

No Breaking Change

CI Settings

### **CI Usage** **Tip**: Check the CI you want to run below, and then comment `/run-ci`. **CI Switch** - [x] Web3 Compatible Tests - [x] OCT 1-5 And 12-15 - [ ] OCT 6-10 - [ ] OCT 11 - [ ] OCT 16-19 - [x] v3 Core Tests ### **CI Description** | CI Name | Description | | ----------------------------------------- | ------------------------------------------------------------------------- | | *Web3 Compatible Test* | Test the Web3 compatibility of Axon | | *v3 Core Test* | Run the compatibility tests provided by Uniswap V3 | | *OCT 1-5 \| 6-10 \| 11 \| 12-15 \| 16-19* | Run the compatibility tests provided by OpenZeppelin |

[KaoImin]

/run-ci

[github-actions[bot]]

CI tests run on commit:

• commit id: https://github.com/axonweb3/axon/commit/04dc08def8b1a389121e0c15be0e57612368864d

CI test list:

• OCT 1-5 And 12-15
• v3 Core Tests
• Web3 Compatible Tests

  Please check ci test results later.