[rtext] Add option to load TTF fonts without anti-aliasing (LoadFontExBitmap)

[Marcos-D]

This PR adds optional support for loading TTF fonts without anti-aliasing, addressing issue #5385.
Fixes #5385

Raylib currently always loads TTF glyphs using FONT_DEFAULT, which applies anti-aliasing.
Pixel-style fonts such as Monogram become blurry when scaled or used in low-resolution UI.

This PR introduces a simple and non-breaking addition that allows users to explicitly request bitmap/no-AA font loading.

A shared internal function handles both AA and non-AA paths:

static Font LoadFontFromMemoryInternal(..., bool antialias)

2. Existing APIs remain unchanged

LoadFontFromMemory() and LoadFontEx() still default to anti-aliasing:

LoadFontFromMemory(..., /* antialias = */ true);

3. New public API for bitmap/no-AA loading

Font LoadFontExBitmap(const char *fileName, int fontSize,
                      const int *codepoints, int codepointCount);

This function loads TTF glyphs using FONT_BITMAP, producing crisp pixel-aligned rendering without smoothing.

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Usage Example

Font aa = LoadFontEx("monogram.ttf", 32, NULL, 0);           // Anti-aliased (default)
Font bitmap = LoadFontExBitmap("monogram.ttf", 32, NULL, 0); // Pixel-perfect, no AA

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Visual Comparison

[raysan5]

@Marcos-D Thanks for the review but I prefer to avoid adding new functions to raylib API to address a very specific use-case scenario.