feat(ci): add OpenHarmony CI and add it to tier2

Author: richerfu

.github/workflows/ci.yml

@@ -236,6 +236,8 @@ jobs:
           - target: s390x-unknown-linux-gnu
           - target: x86_64-unknown-linux-gnux32
           - target: x86_64-unknown-netbsd
+          - target: aarch64-unknown-linux-ohos
+          - target: x86_64-unknown-linux-ohos
 
     steps:
       - name: checkout

README.md

@@ -90,6 +90,9 @@ The following targets are supported by `nix`:
     <li>x86_64-linux-android</li>
     <li>x86_64-unknown-illumos</li>
     <li>x86_64-unknown-netbsd</li>
+    <li>aarch64-unknown-linux-ohos</li>
+    <li>arm-unknown-linux-ohos</li>
+    <li>x86_64-unknown-linux-ohos</li>
    </td>
    <td>
     <li>armv7-unknown-linux-uclibceabihf</li>