[diag] Add new command to factory diags radoi command.

Commit adds new command to factory diag called `radio`.
	- `enable` for enabling the interface to dfault mode,
	- `disable` for disabling the interface

src/core/diags/README.md

@@ -222,6 +222,26 @@ Return the state of the radio.
 sleep
 ```
 
+### diag radio enable
+
+Enable radio interface and put it in receive mode.
+
+```bash
+> diag radio enable
+Radio link started.
+sleep
+```
+
+### diag radio disable
+
+Disable radio interface.
+
+```bash
+> diag radio disable
+Radio link stopped.
+sleep
+```
+
 ### diag rawpowersetting
 
 Show the raw power setting for diagnostics module.

src/core/diags/factory_diags.cpp

@@ -577,6 +577,16 @@ Error Diags::ProcessRadio(uint8_t aArgsLength, char *aArgs[])
             break;
         }
     }
+    else if (StringMatch(aArgs[0], "enable"))
+    {
+        SuccessOrExit(error = Get<Radio>().Enable());
+        Output("Radio link started.\r\n");
+    }
+    else if (StringMatch(aArgs[0], "disable"))
+    {
+        SuccessOrExit(error = Get<Radio>().Disable());
+        Output("Radio link stopped.\r\n");
+    }
 
 exit:
     AppendErrorResult(error);

src/core/diags/factory_diags.hpp

@@ -184,6 +184,9 @@ class Diags : public InstanceLocator, private NonCopyable
     Error ProcessGpio(uint8_t aArgsLength, char *aArgs[]);
     Error ProcessPower(uint8_t aArgsLength, char *aArgs[]);
     Error ProcessRadio(uint8_t aArgsLength, char *aArgs[]);
+#if !OPENTHREAD_RADIO
+    Error ProcessLinkRaw(uint8_t aArgsLength, char *aArgs[]);
+#endif
     Error ProcessRepeat(uint8_t aArgsLength, char *aArgs[]);
     Error ProcessPowerSettings(uint8_t aArgsLength, char *aArgs[]);
     Error ProcessRawPowerSetting(uint8_t aArgsLength, char *aArgs[]);