Add examples for HTTP instance APIs. (#2043)

### What problem does this PR solve?

Add examples for HTTP instance APIs.

Issue link: #1937 

### Type of change

- [x] Other (please describe): examples.

Author: vsian

example/http/show_metrics.sh

@@ -12,6 +12,78 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# create table 'my_table'
+echo -e '-- create my_table'
+curl --request POST \
+     --url http://localhost:23820/databases/default_db/tables/my_table \
+     --header 'accept: application/json' \
+     --header 'content-type: application/json' \
+     --data ' {
+         "create_option": "ignore_if_exists",
+         "fields": [
+            {
+                "name" : "num",
+                "type" : "integer"
+            },
+            {
+                "name" : "name",
+                "type" : "varchar"
+            },
+            {
+                "name" : "score",
+                "type" : "float"
+            }
+        ]
+    } '
+
+echo -e '\n\n-- insert 5 rows into my_table'
+curl --request POST \
+     --url http://localhost:23820/databases/default_db/tables/my_table/docs \
+     --header 'accept: application/json' \
+     --header 'content-type: application/json' \
+     --data '
+     [
+        {
+            "num" : 1,
+            "name" : "Tom",
+            "score" : 90
+        },
+        {
+            "num" : 2,
+            "name" : "Henry",
+            "score" : 70
+        },
+        {
+            "num" : 3,
+            "name" : "james",
+            "score" : 70
+        },
+        {
+            "num" : 4,
+            "name" : "Toby",
+            "score" : 92
+        },
+        {
+            "num" : 5,
+            "name" : "Tom",
+            "score" : 90
+        }
+    ] '
+
+# show all rows of 'my_table'
+echo -e '\n\n-- select all rows of my_table'
+curl --request GET \
+     --url http://localhost:23820/databases/default_db/tables/my_table/docs \
+     --header 'accept: application/json' \
+     --header 'content-type: application/json' \
+     --data '
+     {
+         "output":
+         [
+             "*"
+         ]
+     } '
+
 # show buffer
 echo -e '\n-- show buffer'
 curl --request GET \
@@ -36,3 +108,79 @@ curl --request GET \
      --url http://localhost:23820/instance/queries \
      --header 'accept: application/json'
 
+# show logs
+echo -e '\n\n-- show logs'
+curl --request GET \
+     --url http://localhost:23820/instance/logs \
+     --header 'accept: application/json'
+
+# show delta checkpoints
+echo -e '\n\n-- show delta checkpoint'
+curl --request GET \
+     --url http://localhost:23820/instance/delta_checkpoint \
+     --header 'accept: application/json'
+
+# show global checkpoints
+echo -e '\n\n-- show global checkpoint'
+curl --request GET \
+     --url http://localhost:23820/instance/global_checkpoint \
+     --header 'accept: application/json'
+
+# show transactions
+echo -e '\n\n-- show transactions'
+curl --request GET \
+     --url http://localhost:23820/instance/transactions \
+     --header 'accept: application/json'
+
+# show objects
+echo -e '\n\n-- show objects'
+curl --request GET \
+     --url http://localhost:23820/instance/objects \
+     --header 'accept: application/json'
+
+# show files
+echo -e '\n\n-- show files'
+curl --request GET \
+     --url http://localhost:23820/instance/files \
+     --header 'accept: application/json'
+
+# show memory
+echo -e '\n\n-- show memory'
+curl --request GET \
+     --url http://localhost:23820/instance/memory \
+     --header 'accept: application/json'
+
+# show memory objects
+echo -e '\n\n-- show memory objects'
+curl --request GET \
+     --url http://localhost:23820/instance/memory/objects \
+     --header 'accept: application/json'
+
+# show memory allocations
+echo -e '\n\n-- show memory allocations'
+curl --request GET \
+     --url http://localhost:23820/instance/memory/allocations \
+     --header 'accept: application/json'
+
+# show memory allocations
+echo -e '\n\n-- show memory allocations'
+curl --request GET \
+     --url http://localhost:23820/instance/memory/allocations \
+     --header 'accept: application/json'
+
+# force global checkpoints
+echo -e '\n\n-- show memory allocations'
+curl --request POST \
+    --url http://localhost:23820/instance/flush \
+    --header 'accept: application/json'
+
+# compact table
+curl --request POST \
+    --url http://localhost:23820/instance/table/compact \
+    --header 'accept: application/json' \
+    --header 'content-type: application/json' \
+    --data ' 
+    {
+        "db_name" : "default_db",
+        "table_name" : "my_table"
+    } '