perf(macros): use `#[sails_rs::event]` macro to generate encoding code for event, remove runtime BTreeMaps

### File Location(s)

_No response_

### Proposal

Use `#[sails_rs::event]` macro to generate encoding code for event, remove runtime BTreeMaps

```rust
#[sails_rs::event]
pub enum CounterEvents {
    /// Emitted when a new value is added to the counter
    Added(u32),
    /// Emitted when a value is subtracted from the counter
    Subtracted(u32),
}

```