custom fontWeight numeric values for Text on Android (facebook#25341)

Summary:
I found that on Android we only support 2 fontWeight options, either **normal** or **bold**, even developer can set any numeric value. But iOS supports all possible numeric values. This PR tries to add support for all possible numeric values on Android, even if it's supported only on Android P(28) and above.

This change might break texts where fontWeight use improperly, because this PR removes conversion of values above 500 to BOLD and below 500 to normal.

FYI, also moved **mCustomTypefaceCache** usage up because it was working after unnecessary mFontCache usage.

## Changelog

[Android] [Changed] - add custom font weight support to Text component on Android, only on P(API 28) and above versions.
Pull Request resolved: facebook#25341

Test Plan: RNTester app's Text examples will show Rubik Regular, Rubik Light, Rubik Bold, Rubik Medium and Rubik Medium Italic texts in corresponding font family, style and weights.

Differential Revision: D15956350

Pulled By: mdvacca

fbshipit-source-id: 61079d953c65fb34ab4497d44c22317912a5a616

Author: dulmandakh

RNTester/android/app/src/main/java/com/facebook/react/uiapp/RNTesterApplication.java

@@ -47,7 +47,7 @@ public List<ReactPackage> getPackages() {
 
   @Override
   public void onCreate() {
-    ReactFontManager.getInstance().addCustomFont(this, "Srisakdi", R.font.srisakdi);
+    ReactFontManager.getInstance().addCustomFont(this, "Rubik", R.font.rubik);
     super.onCreate();
   }
 

RNTester/android/app/src/main/res/font/rubik.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<font-family xmlns:app="http://schemas.android.com/apk/res-auto">
+  <font app:fontStyle="normal" app:fontWeight="300" app:font="@font/rubik_light"/>
+  <font app:fontStyle="normal" app:fontWeight="400" app:font="@font/rubik_regular"/>
+  <font app:fontStyle="normal" app:fontWeight="500" app:font="@font/rubik_medium" />
+  <font app:fontStyle="normal" app:fontWeight="700" app:font="@font/rubik_bold" />
+  <font app:fontStyle="italic" app:fontWeight="500" app:font="@font/rubik_medium_italic" />
+</font-family>