Fix DuckDB LOAD syntax support

[benfdking]

Related to #882

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[github-actions]

Benchmark for caac59b

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Test	Base	PR	%
DepthMap::from_parent	40.3±0.35µs	40.6±0.26µs	+0.74%
fix_complex_query	11.9±0.30ms	11.7±0.22ms	-1.68%
parse_complex_query	2.9±0.04µs	2.8±0.04µs	-3.45%
parse_expression_recursion	5.1±0.02µs	5.0±0.07µs	-1.96%
parse_simple_query	821.9±20.28ns	819.0±29.50ns	-0.35%

[github-actions]

Benchmark for 5cfd613

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Test	Base	PR	%
DepthMap::from_parent	41.5±1.56µs	42.0±0.28µs	+1.20%
fix_complex_query	11.9±0.14ms	11.9±0.09ms	0.00%
parse_complex_query	2.9±0.04µs	2.9±0.04µs	0.00%
parse_expression_recursion	5.1±0.03µs	5.1±0.05µs	0.00%
parse_simple_query	818.5±11.23ns	825.5±31.34ns	+0.86%

[github-actions]

Benchmark for 45cb468

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Test	Base	PR	%
DepthMap::from_parent	41.4±0.30µs	41.2±0.26µs	-0.48%
fix_complex_query	11.7±0.27ms	11.6±0.16ms	-0.85%
parse_complex_query	2.9±0.04µs	2.9±0.05µs	0.00%
parse_expression_recursion	5.1±0.06µs	5.1±0.05µs	0.00%
parse_simple_query	828.3±26.53ns	848.1±27.94ns	+2.39%

[github-actions]

Benchmark for 1efa34d

Click to view benchmark

Test	Base	PR	%
DepthMap::from_parent	41.6±0.61µs	41.6±0.39µs	0.00%
fix_complex_query	11.5±0.12ms	11.6±0.09ms	+0.87%
parse_complex_query	2.9±0.04µs	2.9±0.03µs	0.00%
parse_expression_recursion	5.1±0.07µs	5.1±0.07µs	0.00%
parse_simple_query	829.7±16.55ns	857.0±73.79ns	+3.29%