feat(icom): the ATU can be taken out of line

TUNE (1C 01 02) started a cycle; nothing sent the 0 that puts the tuner back
through. An ATU chip beside SPLIT now toggles it, and the tuner state is read
on the slow front-panel beat so the radio's own TUNER button stays in sync.

frontend/wailsjs/go/main/App.d.ts

@@ -646,6 +646,8 @@ export function IcomSetANF(arg1:boolean):Promise<void>;
 
 export function IcomSetAPF(arg1:boolean):Promise<void>;
 
+export function IcomSetATU(arg1:boolean):Promise<void>;
+
 export function IcomSetAntenna(arg1:number):Promise<void>;
 
 export function IcomSetAntiVOX(arg1:number):Promise<void>;