fix: fontWeight typings (#42707)

Summary:
This PR fixes the typings for `fontWeight` style prop. Flow file has below typings but they were missing in typescript file.

```
  fontWeight?:
    | 'normal'
    | 'bold'
    | '100'
    | '200'
    | '300'
    | '400'
    | '500'
    | '600'
    | '700'
    | '800'
    | '900'
    | 100
    | 200
    | 300
    | 400
    | 500
    | 600
    | 700
    | 800
    | 900
    | 'ultralight'
    | 'thin'
    | 'light'
    | 'medium'
    | 'regular'
    | 'semibold'
    | 'condensedBold'
    | 'condensed'
    | 'heavy'
    | 'black'
    | undefined;
```

## Changelog:

[GENERAL] [ADDED] - Added missing typings for fontWeight style prop.

Pull Request resolved: https://github.com/facebook/react-native/pull/42707

Test Plan: Tested manually.

Reviewed By: cortinico

Differential Revision: D53191119

Pulled By: NickGerleman

fbshipit-source-id: 47c00ea81be5aa217d57be0609cfc7bd4e8e6843

packages/react-native/Libraries/StyleSheet/StyleSheetTypes.d.ts

@@ -326,6 +326,25 @@ export interface TextStyle extends TextStyleIOS, TextStyleAndroid, ViewStyle {
     | '700'
     | '800'
     | '900'
+    | 100
+    | 200
+    | 300
+    | 400
+    | 500
+    | 600
+    | 700
+    | 800
+    | 900
+    | 'ultralight'
+    | 'thin'
+    | 'light'
+    | 'medium'
+    | 'regular'
+    | 'semibold'
+    | 'condensedBold'
+    | 'condensed'
+    | 'heavy'
+    | 'black'
     | undefined;
   letterSpacing?: number | undefined;
   lineHeight?: number | undefined;