Compatible with negative page number and size (#5311)

#### What type of PR is this?

/kind bug
/area core
/milestone 2.13.x

#### What this PR does / why we need it:

This PR makes Halo compatible with negative page number and size parameters to resolve <#5298>.

#### Which issue(s) this PR fixes:

Fixes #5298

#### Special notes for your reviewer:

Try to install [Hao theme](https://github.com/liuzhihang/halo-theme-hao/releases/tag/v1.4.7) and [Chirpy theme](https://github.com/AirboZH/halo-theme-chirpy/releases/tag/v1.3.3) and check the frontend pages.

#### Does this PR introduce a user-facing change?

```release-note
修复因限制分页参数导致部分主题页面无法正常渲染的问题。
```

api/src/main/java/run/halo/app/extension/PageRequestImpl.java

@@ -13,8 +13,12 @@ public class PageRequestImpl implements PageRequest {
 
     public PageRequestImpl(int pageNumber, int pageSize, Sort sort) {
         Assert.notNull(sort, "Sort must not be null");
-        Assert.isTrue(pageNumber >= 0, "Page index must not be less than zero!");
-        Assert.isTrue(pageSize >= 0, "Page size must not be less than one!");
+        if (pageNumber < 1) {
+            pageNumber = 1;
+        }
+        if (pageSize < 0) {
+            pageSize = 0;
+        }
         this.pageNumber = pageNumber;
         this.pageSize = pageSize;
         this.sort = sort;

api/src/test/java/run/halo/app/extension/PageRequestImplTest.java

@@ -0,0 +1,27 @@
+package run.halo.app.extension;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.Random;
+import org.junit.jupiter.api.RepeatedTest;
+import org.springframework.data.domain.Sort;
+
+class PageRequestImplTest {
+
+    @RepeatedTest(10)
+    void shouldBeCompatibleZeroAndNegativePageNumber() {
+        var randomPageNumber = -(new Random().nextInt(0, Integer.MAX_VALUE));
+        var page = new PageRequestImpl(randomPageNumber, 10, Sort.unsorted());
+        assertEquals(1, page.getPageNumber());
+        assertEquals(10, page.getPageSize());
+    }
+
+    @RepeatedTest(10)
+    void shouldBeCompatibleNegativePageSize() {
+        var randomPageSize = -(new Random().nextInt(1, Integer.MAX_VALUE));
+        var page = new PageRequestImpl(10, randomPageSize, Sort.unsorted());
+        assertEquals(10, page.getPageNumber());
+        assertEquals(0, page.getPageSize());
+    }
+
+}