Epic: Protocol 22 Changes

[Shaptic]

Protocol 22: Constructors

This epic defines all Horizon and SDK work that pertains to Protocol 22.

References:

• Core Timeline
• CAP-58: Soroban Constructors
• High-performance HTTP server: stellar/stellar-core#4350
• All Platform Protocol 22 issues: projects#37/32

Note: All work should target a feature branch: RPC is v22-breaking-changes and the Go monorepo is protocol-22.

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Phase 1: Support

This phase involves adding support for all of the plumbing we'll need for the actual feature work:

• [x] Generate new protocol definitions:
  • [x] Update Horizon to use new XDR: https://github.com/stellar/go/issues/5423
  • [x] Update RPC to use new XDR: Doable once the above is released.
  • [x] stellar/js-stellar-base#768
• [x] Update preflight to support both Protocol 21 & 22 hosts / XDR: https://github.com/stellar/soroban-rpc/pull/264
• [x] https://github.com/stellar/go/issues/5426

Phase 2: Integration

This phase involves incorporating Core's changes across the stack as well as our own breaking changes:

• Handle the new host function: #5437
• Refactoring RPC endpoints:
  • [ ] https://github.com/stellar/soroban-rpc/issues/269
  • [x] https://github.com/stellar/soroban-rpc/issues/258
  • [x] #5455
• Remove deprecated Horizon fields:
  • [x] https://github.com/stellar/go/issues/5438