Add [Flags] attribute to multiple enums in SDL3

This commit introduces the `[Flags]` attribute to several enumerations in the `Hexa.NET.SDL3` namespace. The affected enums include `SDLGPUColorComponentFlags`, `SDLInitFlags`, `SDLKeymod`, `SDLMessageBoxFlags`, `SDLMouseButtonFlags`, and `SDLWindowFlags`. This enhancement allows for bitwise operations on the enum values, enabling the combination of multiple flags in a single variable, thus improving flexibility and usability in scenarios requiring multiple options.

Author: JunaMeinhold

Hexa.NET.SDL3/SDLGPUColorComponentFlags.cs

@@ -12,6 +12,7 @@
 
 namespace Hexa.NET.SDL3
 {
+	[Flags]
 	public enum SDLGPUColorComponentFlags : byte
 	{
 		R = (byte)(1u<<0),

Hexa.NET.SDL3/SDLInitFlags.cs

@@ -12,7 +12,8 @@
 
 namespace Hexa.NET.SDL3
 {
-	public enum SDLInitFlags : uint
+    [Flags]
+    public enum SDLInitFlags : uint
 	{
 		Timer = 0x00000001u,
 		Audio = 0x00000010u,

Hexa.NET.SDL3/SDLKeymod.cs

@@ -12,7 +12,8 @@
 
 namespace Hexa.NET.SDL3
 {
-	public enum SDLKeymod : ushort
+    [Flags]
+    public enum SDLKeymod : ushort
 	{
 		None = unchecked((ushort)0x0000u),
 		Lshift = unchecked((ushort)0x0001u),

Hexa.NET.SDL3/SDLMessageBoxFlags.cs

@@ -12,7 +12,8 @@
 
 namespace Hexa.NET.SDL3
 {
-	public enum SDLMessageBoxFlags : uint
+    [Flags]
+    public enum SDLMessageBoxFlags : uint
 	{
 		Error = 0x00000010u,
 		Warning = 0x00000020u,

Hexa.NET.SDL3/SDLMouseButtonFlags.cs

@@ -12,7 +12,8 @@
 
 namespace Hexa.NET.SDL3
 {
-	public enum SDLMouseButtonFlags : uint
+    [Flags]
+    public enum SDLMouseButtonFlags : uint
 	{
 		Left = 1,
 		Middle = 2,

Hexa.NET.SDL3/SDLWindowFlags.cs

@@ -13,7 +13,8 @@
 
 namespace Hexa.NET.SDL3
 {
-	public enum SDLWindowFlags : uint
+    [Flags]
+    public enum SDLWindowFlags : uint
 	{
 		Fullscreen = (0x0000000000000001),
 		Opengl = (0x0000000000000002),