acp_thread: Preserve waiting tool call status on updates

[benbrandt]

Allows contents to update without dropping the permission (caused by
claude subagents)

Closes
agentclientprotocol/claude-agent-acp#708

Self-Review Checklist:

• I've reviewed my own diff for quality, security, and reliability
• Unsafe blocks (if any) have justifying comments
• The content is consistent with the UI/UX checklist
• Tests cover the new/changed behavior
• Performance impact has been considered and is acceptable

Release Notes:

• acp: Fix failed permissions requests for external agents

[benbrandt]

@bennetbo I dug in to the issue you were worried about and I think we are actually ok, because we replace once we send the response:

zed/crates/acp_thread/src/acp_thread.rs

Lines 2433 to 2450 in 6ccafcc

	let new_status =
	if is_action_choice {
	ToolCallStatus::InProgress
	} else {
	match outcome.option_kind {
	acp::PermissionOptionKind::RejectOnce
	| acp::PermissionOptionKind::RejectAlways => ToolCallStatus::Rejected,
	acp::PermissionOptionKind::AllowOnce
	| acp::PermissionOptionKind::AllowAlways => ToolCallStatus::InProgress,
	_ => ToolCallStatus::InProgress,
	}
	};
	let curr_status = mem::replace(&mut call.status, new_status);
	if let ToolCallStatus::WaitingForConfirmation { respond_tx, .. } = curr_status {
	respond_tx.send(outcome).ok();
	}