feat: support expr in values clause of multi table insert

[SkyFan2002]

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Summary

1. Improved syntax:

intoClause ::=
  INTO <target_table> [ ( <target_col_name> [ , ... ] ) ] [VALUES( { Expr | DEFAULT } [ , ... ] ) ]

2. Deal with default ambiguity
   While in snowflake DEFAULT(represents a default value) and a ident named default is ambiguous:
   

in our implemention the column name in source of multi-table insert can't be default:

:) create or replace table t1(c1 int,c2 int);

CREATE
OR REPLACE TABLE t1(c1 int, c2 int)

:) create or replace table t2(c1 int,c2 int);

CREATE
OR REPLACE TABLE t2(c1 int, c2 int)

:) create or replace table s(c3 int,default int);

CREATE
OR REPLACE TABLE s(c3 int, DEFAULT int)

:) insert into s values(1,2),(3,4),(5,6);

INSERT INTO
  s
VALUES
(1, 2),
(3, 4),
(5, 6)

3 rows written in 0.112 sec. Processed 3 rows, 26 B (26.82 rows/s, 232 B/s)

:) INSERT FIRST
    WHEN c3 = 5 THEN
      INTO t1
    WHEN c3 > 0 THEN
      INTO t2 values(c3, default)
SELECT * from s;
error: APIError: ResponseError with 1006: The column name in source of multi-table insert can't be 'default'

It is recommended to use aliases to bypass this restriction:

INSERT FIRST
    WHEN c3 = 5 THEN
      INTO t1
    WHEN c3 > 0 THEN
      INTO t2 values(c3, c4)
SELECT c3,default as c4 from s;

• part of Tracking: Multi-table insert statement #15141

Tests

• Unit Test
• Logic Test
• Benchmark Test
• No Test - Explain why

Type of change

• Bug Fix (non-breaking change which fixes an issue)
• New Feature (non-breaking change which adds functionality)
• Breaking Change (fix or feature that could cause existing functionality not to work as expected)
• Documentation Update
• Refactoring
• Performance Improvement
• Other (please describe):

[dantengsky]

LGTM