fix agent tests model preferences state (#5828)

In the agent tests, the `testing/reset` command was not entirely
resetting
the state between tests. This meant that 2 tests (explain and smell)
that
performed explicit `chat/setModel` requests to change the model to
Mixtral but
were (incorrectly) running with the chat model used for the previous
tests.

The reason is that `testing/reset` just cleared the in-memory
`LocalStorageProvider` backing `Map` and did not cause
`LocalStorageProvider` to fire a change event, which is necessary for
the
`ModelsService` to know that the models preferences changed.

Also clean up types.

## Test plan

Agent tests

agent/bindings/kotlin/lib/src/main/kotlin/com/sourcegraph/cody/agent/protocol_generated/CodyAgentServer.kt

@@ -22,8 +22,6 @@ interface CodyAgentServer {
   fun chat_sidebar_new(params: Null?): CompletableFuture<Chat_Sidebar_NewResult>
   @JsonRequest("chat/delete")
   fun chat_delete(params: Chat_DeleteParams): CompletableFuture<List<ChatExportResult>>
-  @JsonRequest("chat/restore")
-  fun chat_restore(params: Chat_RestoreParams): CompletableFuture<String>
   @JsonRequest("chat/models")
   fun chat_models(params: Chat_ModelsParams): CompletableFuture<Chat_ModelsResult>
   @JsonRequest("chat/export")

agent/protocol.md

@@ -58,13 +58,7 @@ shutdown: [null, null]
 ```ts
 'chat/new': [null, string]
 ```
-<h2 id="chat_restore"><a href="#chat_restore" name="chat_restore"><code>chat/restore</code> (<img class="emoji" title=":arrow_right:" alt=":arrow_right:" src="https://github.githubassets.com/images/icons/emoji/unicode/27a1.png" height="20" width="20">)</a></h2>
-<p>Request sent from the client to client server.</p>
-
 
-```ts
-'chat/restore': [{ modelID: string; messages: AgentChatMessage[]; chatID: string; }, string]
-```
 <h2 id="chat_models"><a href="#chat_models" name="chat_models"><code>chat/models</code> (<img class="emoji" title=":arrow_right:" alt=":arrow_right:" src="https://github.githubassets.com/images/icons/emoji/unicode/27a1.png" height="20" width="20">)</a></h2>
 <p>Request sent from the client to client server.</p>