Support setting font feature values (zed-industries#11898)

Now (on `macOS` and `Windows`) we can set font feature value:
```rust
  "buffer_font_features": {
    "cv01": true,
    "cv03": 3,
    "cv09": 1,
    "VSAH": 7,
    "VSAJ": 8
  }
```

And one can still use `"cv01": true`.



https://github.com/zed-industries/zed/assets/14981363/3e3fcf4f-abdb-4d9e-a0a6-71dc24a515c2




Release Notes:

- Added font feature values, now you can set font features like `"cv01":
7`.

---------

Co-authored-by: Mikayla <[email protected]>

crates/gpui/src/platform/mac/open_type.rs

@@ -30,14 +30,11 @@ pub fn apply_features(font: &mut Font, features: &FontFeatures) {
         let native_font = font.native_font();
         let mut feature_array =
             CFArrayCreateMutable(kCFAllocatorDefault, 0, &kCFTypeArrayCallBacks);
-        for (tag, enable) in features.tag_value_list() {
-            if !enable {
-                continue;
-            }
+        for (tag, value) in features.tag_value_list() {
             let keys = [kCTFontOpenTypeFeatureTag, kCTFontOpenTypeFeatureValue];
             let values = [
                 CFString::new(&tag).as_CFTypeRef(),
-                CFNumber::from(1).as_CFTypeRef(),
+                CFNumber::from(*value as i32).as_CFTypeRef(),
             ];
             let dict = CFDictionaryCreate(
                 kCFAllocatorDefault,

crates/gpui/src/platform/windows/direct_write.rs

@@ -1201,26 +1201,26 @@ fn apply_font_features(
 
     // All of these features are enabled by default by DirectWrite.
     // If you want to (and can) peek into the source of DirectWrite
-    let mut feature_liga = make_direct_write_feature("liga", true);
-    let mut feature_clig = make_direct_write_feature("clig", true);
-    let mut feature_calt = make_direct_write_feature("calt", true);
+    let mut feature_liga = make_direct_write_feature("liga", 1);
+    let mut feature_clig = make_direct_write_feature("clig", 1);
+    let mut feature_calt = make_direct_write_feature("calt", 1);
 
-    for (tag, enable) in tag_values {
-        if tag == *"liga" && !enable {
+    for (tag, value) in tag_values {
+        if tag.as_str() == "liga" && *value == 0 {
             feature_liga.parameter = 0;
             continue;
         }
-        if tag == *"clig" && !enable {
+        if tag.as_str() == "clig" && *value == 0 {
             feature_clig.parameter = 0;
             continue;
         }
-        if tag == *"calt" && !enable {
+        if tag.as_str() == "calt" && *value == 0 {
             feature_calt.parameter = 0;
             continue;
         }
 
         unsafe {
-            direct_write_features.AddFontFeature(make_direct_write_feature(&tag, enable))?;
+            direct_write_features.AddFontFeature(make_direct_write_feature(&tag, *value))?;
         }
     }
     unsafe {
@@ -1233,18 +1233,11 @@ fn apply_font_features(
 }
 
 #[inline]
-fn make_direct_write_feature(feature_name: &str, enable: bool) -> DWRITE_FONT_FEATURE {
+fn make_direct_write_feature(feature_name: &str, parameter: u32) -> DWRITE_FONT_FEATURE {
     let tag = make_direct_write_tag(feature_name);
-    if enable {
-        DWRITE_FONT_FEATURE {
-            nameTag: tag,
-            parameter: 1,
-        }
-    } else {
-        DWRITE_FONT_FEATURE {
-            nameTag: tag,
-            parameter: 0,
-        }
+    DWRITE_FONT_FEATURE {
+        nameTag: tag,
+        parameter,
     }
 }