feat: add missing const qualifiers (#2233)

* feat: make `ViewPort` getters const
* feat: make tx-buffers const
* feat: make `canvas_get_buffer_size` const
* feat: make `canvas` methods const
* feat: make `icon_animation` methods const
* feat: make `scene_manager` methods const
* feat: make `loader` method const
* feat: make `canvas_get_font_params` const

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

applications/services/gui/canvas.c

@@ -57,7 +57,7 @@ uint8_t* canvas_get_buffer(Canvas* canvas) {
     return u8g2_GetBufferPtr(&canvas->fb);
 }
 
-size_t canvas_get_buffer_size(Canvas* canvas) {
+size_t canvas_get_buffer_size(const Canvas* canvas) {
     furi_assert(canvas);
     return u8g2_GetBufferTileWidth(&canvas->fb) * u8g2_GetBufferTileHeight(&canvas->fb) * 8;
 }
@@ -75,17 +75,17 @@ void canvas_frame_set(
     canvas->height = height;
 }
 
-uint8_t canvas_width(Canvas* canvas) {
+uint8_t canvas_width(const Canvas* canvas) {
     furi_assert(canvas);
     return canvas->width;
 }
 
-uint8_t canvas_height(Canvas* canvas) {
+uint8_t canvas_height(const Canvas* canvas) {
     furi_assert(canvas);
     return canvas->height;
 }
 
-uint8_t canvas_current_font_height(Canvas* canvas) {
+uint8_t canvas_current_font_height(const Canvas* canvas) {
     furi_assert(canvas);
     uint8_t font_height = u8g2_GetMaxCharHeight(&canvas->fb);
 
@@ -96,10 +96,10 @@ uint8_t canvas_current_font_height(Canvas* canvas) {
     return font_height;
 }
 
-CanvasFontParameters* canvas_get_font_params(Canvas* canvas, Font font) {
+const CanvasFontParameters* canvas_get_font_params(const Canvas* canvas, Font font) {
     furi_assert(canvas);
     furi_assert(font < FontTotalNumber);
-    return (CanvasFontParameters*)&canvas_font_params[font];
+    return &canvas_font_params[font];
 }
 
 void canvas_clear(Canvas* canvas) {