feat: implement count_hash aggr function (#6342)

* feat: implement count_hash aggr function

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>

* sqlness case

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>

* change copyright year

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>

* review changes

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>

---------

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>

tests/cases/standalone/common/function/count_hash.result

@@ -0,0 +1,60 @@
+create table
+    t (
+        ts timestamp time index,
+        `id` int,
+        `name` string,
+        PRIMARY KEY (`id`),
+    );
+
+Affected Rows: 0
+
+insert into
+    t (ts, `id`, `name`)
+values
+    (1, 1, 'a'),
+    (2, 2, 'b'),
+    (3, 3, 'c'),
+    (4, 4, 'd');
+
+Affected Rows: 4
+
+select
+    count_hash (`id`)
+from
+    t;
+
++------------------+
+| count_hash(t.id) |
++------------------+
+| 4                |
++------------------+
+
+select
+    count_hash (`id`)
+from
+    t
+group by
+    `name`;
+
++------------------+
+| count_hash(t.id) |
++------------------+
+| 1                |
+| 1                |
+| 1                |
+| 1                |
++------------------+
+
+select
+    count_hash (`id`, `name`)
+from
+    t
+group by
+    ts;
+
+Error: 3001(EngineExecuteQuery), This feature is not implemented: count_hash with multiple arguments
+
+drop table t;
+
+Affected Rows: 0
+

tests/cases/standalone/common/function/count_hash.sql

@@ -0,0 +1,36 @@
+create table
+    t (
+        ts timestamp time index,
+        `id` int,
+        `name` string,
+        PRIMARY KEY (`id`),
+    );
+
+insert into
+    t (ts, `id`, `name`)
+values
+    (1, 1, 'a'),
+    (2, 2, 'b'),
+    (3, 3, 'c'),
+    (4, 4, 'd');
+
+select
+    count_hash (`id`)
+from
+    t;
+
+select
+    count_hash (`id`)
+from
+    t
+group by
+    `name`;
+
+select
+    count_hash (`id`, `name`)
+from
+    t
+group by
+    ts;
+
+drop table t;