telemetry_events: Rename AssistantEvent to AssistantEventData (#28133)

This PR renames the `AssistantEvent` type to `AssistantEventData`, as it
no longer represents the event itself, just the data needed to construct
it.

Pulling out of https://github.com/zed-industries/zed/pull/25179.

Release Notes:

- N/A

crates/agent/src/terminal_inline_assistant.rs

@@ -18,7 +18,7 @@ use language_model::{
 };
 use prompt_store::PromptBuilder;
 use std::sync::Arc;
-use telemetry_events::{AssistantEvent, AssistantKind, AssistantPhase};
+use telemetry_events::{AssistantEventData, AssistantKind, AssistantPhase};
 use terminal_view::TerminalView;
 use ui::prelude::*;
 use util::ResultExt;
@@ -292,7 +292,7 @@ impl TerminalInlineAssistant {
                 let codegen = assist.codegen.read(cx);
                 let executor = cx.background_executor().clone();
                 report_assistant_event(
-                    AssistantEvent {
+                    AssistantEventData {
                         conversation_id: None,
                         kind: AssistantKind::InlineTerminal,
                         message_id: codegen.message_id.clone(),