MDEV-9695: Wrong window frame when using RANGE BETWEEN N FOLLOWING AND PRECEDING

Part#2: Fix a couple more issues in rows-type frames.
This also has a code cleanup:
- introduce a separate Frame_rows_current_row_(top,bottom). This is
  is a special case which doesn't need its cursor or partition bound check
- Split Frame_n_rows into
  = Frame_n_rows_preceding (this one is now much simpler)
  = Frame_n_rows_following (simpler and works but may need some work still)

Author: spetrunia

mysql-test/r/win.result

@@ -683,4 +683,101 @@ pk	a	b	bit_or
 6	2	64	224
 7	2	128	208
 8	2	16	144
+# Extra ROWS n PRECEDING tests 
+select pk, a, b,
+bit_or(b) over (partition by a order by pk ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING) as bit_or
+from t1;
+pk	a	b	bit_or
+1	0	1	0
+2	0	2	1
+3	1	4	0
+4	1	8	4
+5	2	32	0
+6	2	64	32
+7	2	128	64
+8	2	16	128
 drop table t1;
+create table t2 (
+pk int, 
+a int, 
+b int
+);
+insert into t2 values
+( 1, 0, 1),
+( 2, 0, 2),
+( 3, 0, 4),
+( 4, 0, 8),
+( 5, 1, 16),
+( 6, 1, 32),
+( 7, 1, 64),
+( 8, 1, 128),
+( 9, 2, 256),
+(10, 2, 512),
+(11, 2, 1024),
+(12, 2, 2048);
+select pk, a, b,
+bit_or(b) over (partition by a order by pk ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING) as bit_or
+from t2;
+pk	a	b	bit_or
+1	0	1	0
+2	0	2	1
+3	0	4	2
+4	0	8	4
+5	1	16	0
+6	1	32	16
+7	1	64	32
+8	1	128	64
+9	2	256	0
+10	2	512	256
+11	2	1024	512
+12	2	2048	1024
+select pk, a, b,
+bit_or(b) over (partition by a order by pk ROWS BETWEEN 2 PRECEDING AND 2 PRECEDING) as bit_or
+from t2;
+pk	a	b	bit_or
+1	0	1	0
+2	0	2	0
+3	0	4	1
+4	0	8	2
+5	1	16	0
+6	1	32	0
+7	1	64	16
+8	1	128	32
+9	2	256	0
+10	2	512	0
+11	2	1024	256
+12	2	2048	512
+select pk, a, b,
+bit_or(b) over (partition by a order by pk ROWS BETWEEN 2 PRECEDING AND 1 PRECEDING) as bit_or
+from t2;
+pk	a	b	bit_or
+1	0	1	0
+2	0	2	1
+3	0	4	3
+4	0	8	6
+5	1	16	0
+6	1	32	16
+7	1	64	48
+8	1	128	96
+9	2	256	0
+10	2	512	256
+11	2	1024	768
+12	2	2048	1536
+# Check CURRENT ROW 
+select pk, a, b,
+bit_or(b) over (partition by a order by pk ROWS BETWEEN CURRENT ROW AND CURRENT ROW) as bit_or
+from t2;
+pk	a	b	bit_or
+1	0	1	1
+2	0	2	2
+3	0	4	4
+4	0	8	8
+5	1	16	16
+6	1	32	32
+7	1	64	64
+8	1	128	128
+9	2	256	256
+10	2	512	512
+11	2	1024	1024
+12	2	2048	2048
+drop table t2;

mysql-test/t/win.test

@@ -440,4 +440,50 @@ select pk, a, b,
 bit_or(b) over (partition by a order by pk ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING) as bit_or
 from t1;
 
+--echo # Extra ROWS n PRECEDING tests 
+select pk, a, b,
+bit_or(b) over (partition by a order by pk ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING) as bit_or
+from t1;
 drop table t1;
+
+
+create table t2 (
+  pk int, 
+  a int, 
+  b int
+);
+
+insert into t2 values
+( 1, 0, 1),
+( 2, 0, 2),
+( 3, 0, 4),
+( 4, 0, 8),
+( 5, 1, 16),
+( 6, 1, 32),
+( 7, 1, 64),
+( 8, 1, 128),
+( 9, 2, 256),
+(10, 2, 512),
+(11, 2, 1024),
+(12, 2, 2048);
+
+select pk, a, b,
+bit_or(b) over (partition by a order by pk ROWS BETWEEN 1 PRECEDING AND 1 PRECEDING) as bit_or
+from t2;
+
+select pk, a, b,
+bit_or(b) over (partition by a order by pk ROWS BETWEEN 2 PRECEDING AND 2 PRECEDING) as bit_or
+from t2;
+
+select pk, a, b,
+bit_or(b) over (partition by a order by pk ROWS BETWEEN 2 PRECEDING AND 1 PRECEDING) as bit_or
+from t2;
+
+--echo # Check CURRENT ROW 
+
+select pk, a, b,
+bit_or(b) over (partition by a order by pk ROWS BETWEEN CURRENT ROW AND CURRENT ROW) as bit_or
+from t2;
+
+drop table t2;
+