Show region information in sub-GHz app (#2249)

* Show region info in sub-GHz app
* SubGhz: reset widget on region info scene exit
* Format sources

Co-authored-by: あく <alleteam@gmail.com>

applications/main/subghz/scenes/subghz_scene_region_info.c

@@ -0,0 +1,39 @@
+#include "../subghz_i.h"
+
+#include <furi_hal_region.h>
+
+void subghz_scene_region_info_on_enter(void* context) {
+    SubGhz* subghz = context;
+    const FuriHalRegion* const region = furi_hal_region_get();
+    FuriString* buffer;
+    buffer = furi_string_alloc();
+    if(region) {
+        furi_string_cat_printf(buffer, "Region: %s,  bands:\n", region->country_code);
+        for(uint16_t i = 0; i < region->bands_count; ++i) {
+            furi_string_cat_printf(
+                buffer,
+                "   %lu-%lu kHz\n",
+                region->bands[i].start / 1000,
+                region->bands[i].end / 1000);
+        }
+    } else {
+        furi_string_cat_printf(buffer, "Region: N/A\n");
+    }
+
+    widget_add_string_multiline_element(
+        subghz->widget, 0, 0, AlignLeft, AlignTop, FontSecondary, furi_string_get_cstr(buffer));
+
+    furi_string_free(buffer);
+    view_dispatcher_switch_to_view(subghz->view_dispatcher, SubGhzViewIdWidget);
+}
+
+bool subghz_scene_region_info_on_event(void* context, SceneManagerEvent event) {
+    UNUSED(context);
+    UNUSED(event);
+    return false;
+}
+
+void subghz_scene_region_info_on_exit(void* context) {
+    SubGhz* subghz = context;
+    widget_reset(subghz->widget);
+}