💎 TON testnet integration

[swift1337]

Description

This EPIC groups tasks toward integration of TON into testnet. Features:

User Actions

• donate()
• deposit()
• deposit_and_call()
• withdraw() (on behalf of TSS)

Governance actions

• enable_deposits()
• update_tss()
• update_code()

High-Level task list

• Implement Gateway contract on TON using FunC & Blueprint
  • Create zeta-chain/protocol-contracts-ton repository
  • Determine gas economics for TON integration (including storage fees)
  • Support TSS signature
• TON localnet integration
• Implement TON observer
• TON deposit() E2E test
• Implement TON signer
• TON withdraw() E2E test
• Provision configuration changes (chain_id, chain, observer_chain_params, ...)
• Deploy contract on testnet
• DevX: prepare docs, code samples, tutorials, ...

### Tasks
- [ ] https://github.com/zeta-chain/node/issues/2718
- [ ] https://github.com/zeta-chain/node/issues/2720
- [ ] https://github.com/zeta-chain/node/issues/2757
- [ ] https://github.com/zeta-chain/node/issues/2807
- [ ] https://github.com/zeta-chain/node/issues/2808
- [ ] https://github.com/zeta-chain/node/issues/2809
- [ ] https://github.com/zeta-chain/node/issues/2810
- [ ] https://github.com/zeta-chain/node/issues/2916
- [ ] https://github.com/zeta-chain/node/issues/2935
- [ ] https://github.com/zeta-chain/node/issues/2946
- [ ] https://github.com/zeta-chain/protocol-contracts-ton/issues/14
- [ ] https://github.com/zeta-chain/protocol-contracts-ton/issues/13
- [ ] https://github.com/zeta-chain/protocol-contracts-ton/issues/12
- [ ] https://github.com/zeta-chain/protocol-contracts-ton/issues/9