test: add regression test for unnesting dictionary encoded columns (#… #211

Job	Run time
linux build test	4m 32s
cargo test hash collisions (amd64)	23m 52s
Run sqllogictests with the sqlite test suite	1h 6m 51s
cargo test 'extended_tests' (amd64)	18m 1s
	1h 53m 16s

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