Pass up intent with completion requests (#31710)

This PR adds a new `intent` field to completion requests to assist in
categorizing them correctly.

Release Notes:

- N/A

---------

Co-authored-by: Ben Brandt <benjamin.j.brandt@gmail.com>

crates/agent/src/buffer_codegen.rs

@@ -34,6 +34,7 @@ use std::{
 };
 use streaming_diff::{CharOperation, LineDiff, LineOperation, StreamingDiff};
 use telemetry_events::{AssistantEventData, AssistantKind, AssistantPhase};
+use zed_llm_client::CompletionIntent;
 
 pub struct BufferCodegen {
     alternatives: Vec<Entity<CodegenAlternative>>,
@@ -464,6 +465,7 @@ impl CodegenAlternative {
             LanguageModelRequest {
                 thread_id: None,
                 prompt_id: None,
+                intent: Some(CompletionIntent::InlineAssist),
                 mode: None,
                 tools: Vec::new(),
                 tool_choice: None,