fix: setting letterSpacing prop (#2807)

# Summary

Fixes: #2806 

This PR fixes calculating `letterSpacing` for `Text` when
`letterSpacing` prop type is `Number`.

## Test Plan

Run example from issue: #2806

Author: kacperzolkiewski

android/src/main/java/com/horcrux/svg/FontData.java

@@ -136,7 +136,7 @@ private double toAbsolute(
       ReadableMap font, String prop, double scale, double fontSize, double relative) {
     ReadableType propType = font.getType(prop);
     if (propType == ReadableType.Number) {
-      return font.getDouble(prop);
+      return font.getDouble(prop) * scale;
     } else {
       String string = font.getString(prop);
       return PropHelper.fromRelative(string, relative, scale, fontSize);

apple/Text/RNSVGFontData.mm

@@ -184,7 +184,7 @@ + (instancetype)initWithNSDictionary:(NSDictionary *)font parent:(RNSVGFontData
   id letterSpacing = [font objectForKey:LETTER_SPACING];
   if ([letterSpacing isKindOfClass:NSNumber.class]) {
     NSNumber *ls = letterSpacing;
-    data->wordSpacing = (CGFloat)[ls doubleValue];
+    data->letterSpacing = (CGFloat)[ls doubleValue];
   } else {
     data->letterSpacing =
         letterSpacing ? [RNSVGFontData toAbsoluteWithNSString:letterSpacing fontSize:fontSize] : parent->letterSpacing;