Count distinct boolean

[pjmore]

Which issue does this PR close?

Closes #202 .

What changes are included in this PR?

Modified the method to_array_of_size from ScalarValue to add support for boolean lists.

Are there any user-facing changes?

I don't believe so, I couldn't find any relevant documentation about supported datatypes for COUNT DISTINCT but I'm not sure.

[Dandandan]

@pjmore looks good! Maybe you could also add a test for it?

[codecov-commenter]

Codecov Report

Merging #230 (9e48830) into master (23d02bb) will increase coverage by 0.04%.
The diff coverage is 97.29%.

@@            Coverage Diff             @@
##           master     #230      +/-   ##
==========================================
+ Coverage   76.46%   76.50%   +0.04%     
==========================================
  Files         135      135              
  Lines       23250    23287      +37     
==========================================
+ Hits        17777    17815      +38     
+ Misses       5473     5472       -1     

Impacted Files	Coverage Δ
...tafusion/src/physical_plan/distinct_expressions.rs	91.32% <97.22%> (+1.03%)	⬆️
datafusion/src/scalar.rs	54.14% <100.00%> (+0.11%)	⬆️
datafusion/src/physical_plan/group_scalar.rs	57.64% <0.00%> (+2.35%)	⬆️

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[pjmore]

@Dandandan I've added a test.

[Dandandan]

LGTM

[Dandandan]

@pjmore thanks! Could you fix the clippy error?

[alamb]

This is great @pjmore -- thank you -- I also tested locally and it works as advertised. 👍

> CREATE EXTERNAL TABLE t (a boolean) STORED AS CSV LOCATION '/tmp/foo.csv';
0 rows in set. Query took 0 seconds.
> select count(distinct a) from t;
+-------------------+
| COUNT(DISTINCT a) |
+-------------------+
| 1                 |
+-------------------+
1 rows in set. Query took 0 seconds.

👍