Refactor and add default values to various structs

- Removed `FindMatchingCharacter` declaration from `message_data.h`
- Added default values to `DictionaryEntry` and `MessageData` members
- Marked several methods in `DictionaryEntry`, `MessageData`, and `TextElement` as `const`
- Updated `TextElement` constructor to take `const std::string&`
- Added string constants for text descriptions in `TextElement`
- Updated `TextCommands` vector to use new string constants
- Declared new function `FindMatchingCommand`
- Included `<array>` header in `message_editor.h`
- Changed `width_array` in `MessageEditor` to `std::array` with default initialization
- Removed `list_of_texts_` and `all_dictionaries_` vectors from `MessageEditor`
- Added default values to `GameEntity` members
- Initialized `sheets` array in `PseudoVram`
- Initialized `map_parent_` and `all_tiles_types_` arrays in `Overworld`

src/app/zelda3/common.h

@@ -30,12 +30,12 @@ class GameEntity {
     kProperties = 7,
     kDungeonSprite = 8,
   } entity_type_;
-  int x_;
-  int y_;
-  int game_x_;
-  int game_y_;
-  int entity_id_;
-  uint16_t map_id_;
+  int x_ = 0;
+  int y_ = 0;
+  int game_x_ = 0;
+  int game_y_ = 0;
+  int entity_id_ = 0;
+  uint16_t map_id_ = 0;
 
   auto set_x(int x) { x_ = x; }
   auto set_y(int y) { y_ = y; }