feat(cat): make the DTR/RTS lowering a setting

Both defaults break someone. 0.22.7 lowered the lines on Yaesu and
Kenwood and silenced a TS-990 whose interface needs RTS raised to
transmit; 0.22.8 stopped lowering them and an FT8 station reported its
output power wandering, cured by closing OpsLog — Windows raises both on
open and the interface reads one as PTT.

So it is now a checkbox on those two backends, off by default: that is
how they behaved before any of this. Xiegu keeps lowering them
unconditionally (its own report, its own explicit keying setting), and
the CI-V backend keeps the behaviour it has always had.

frontend/wailsjs/go/models.ts

@@ -1924,6 +1924,7 @@ export namespace main {
 	    kenwood_host: string;
 	    kenwood_port: string;
 	    kenwood_baud: number;
+	    lower_lines: boolean;
 	    icom_port: string;
 	    icom_baud: number;
 	    icom_addr: number;
@@ -1964,6 +1965,7 @@ export namespace main {
 	        this.kenwood_host = source["kenwood_host"];
 	        this.kenwood_port = source["kenwood_port"];
 	        this.kenwood_baud = source["kenwood_baud"];
+	        this.lower_lines = source["lower_lines"];
 	        this.icom_port = source["icom_port"];
 	        this.icom_baud = source["icom_baud"];
 	        this.icom_addr = source["icom_addr"];