feat: add EXECUTE IMMEDIATE statement

[andylokandy]

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Summary

Related #14904
Closes #15200

Adding EXECUTE IMMEDIATE command which is used to execute a SQL script.

Example:

EXECUTE IMMEDIATE $$
BEGIN
    LET x := 1;
    LET y := x + 1;
    LET z RESULTSET := SELECT :y + 1;
    RETURN TABLE(z);
END;
$$;
----
┌───────┐
│ 2 + 1 │
│ UInt8 │
├───────┤
│     3 │
└───────┘

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):

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This change is