pref: improve the structure of ContributorVo (#4645) (#4705)

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#### What type of PR is this?
/kind improvement
/kind api-change
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#### What this PR does / why we need it:
优化ContributorVo格式，支持更多信息。
#### Which issue(s) this PR fixes:
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Fixes #4645

#### Special notes for your reviewer:
none
#### Does this PR introduce a user-facing change?

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```release-note
contributorFinder 支持返回用户元数据、注册信息、用户权限等。
```

application/src/main/java/run/halo/app/theme/finders/vo/ContributorVo.java

@@ -4,6 +4,7 @@
 import lombok.ToString;
 import lombok.Value;
 import run.halo.app.core.extension.User;
+import run.halo.app.extension.MetadataOperator;
 
 /**
  * A value object for {@link run.halo.app.core.extension.User}.
@@ -14,7 +15,8 @@
 @Value
 @ToString
 @Builder
-public class ContributorVo {
+public class ContributorVo implements ExtensionVoOperator {
+
     String name;
 
     String displayName;
@@ -25,6 +27,8 @@ public class ContributorVo {
 
     String permalink;
 
+    MetadataOperator metadata;
+
     /**
      * Convert {@link User} to {@link ContributorVo}.
      *
@@ -39,6 +43,7 @@ public static ContributorVo from(User user) {
             .avatar(user.getSpec().getAvatar())
             .bio(user.getSpec().getBio())
             .permalink(permalink)
+            .metadata(user.getMetadata())
             .build();
     }
 }