Fix l2 operator bug when used with int arrays

[Ngalstyan4]

We need properly copy and cast array elements when int array is bassed and we need floats.
Previusly we were interpreting float* array as an int32* array when calculating distances.

I think this issue does not exist when creating an index since there casts happen before. I also added a test to demonstrate this (was it already tested elsewhere and I missed it?). If you can think of other edge cases, let me know here.

The added tests check operator output when used directly. Below is the diff if I ran the same tests without the bugfix:

@@ -33,7 +33,7 @@
 SELECT ARRAY[0,0,0] <-> ARRAY[2,3,-4];
  ?column?
 ----------
-       29
+      NaN
 (1 row)

 -- with float arrays:
@@ -52,7 +52,7 @@
 SELECT '{1,0,1}' <-> '{0,1,0}'::integer[];
  ?column?
 ----------
-        3
+        0
 (1 row)

 SELECT '{1,0,1}' <=> '{0,1,0}'::integer[];

[github-actions]

Benchmarks

metric	old	new	pct change
recall (after create)	0.740	0.740	-
recall (after insert)	0.754	0.780	+3.45%
select bulk tps	486.766	493.583	+1.40%
select bulk latency (ms)	15.702	15.673	-0.18%
select bulk latency (stddev ms)	3.712	1.760	-52.59%
create latency (ms)	1197.828	1197.734	-0.01%
insert bulk tps	11.514	11.551	+0.32%
insert bulk latency (ms)	86.841	86.565	-0.32%
insert bulk latency (stddev ms)	1.995	3.136	+57.19%
disk usage (bytes)	6348800.000	6348800.000	-

[codecov]

Codecov Report

Merging #243 (28f4264) into main (50c294b) will decrease coverage by 0.42%.
The diff coverage is 64.70%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #243      +/-   ##
==========================================
- Coverage   77.68%   77.26%   -0.42%     
==========================================
  Files          23       23              
  Lines        1685     1698      +13     
  Branches      415      421       +6     
==========================================
+ Hits         1309     1312       +3     
- Misses        191      198       +7     
- Partials      185      188       +3     

Files	Coverage Δ
src/hnsw/utils.h	40.00% <ø> (ø)
src/hnsw.c	79.82% <60.00%> (-2.17%)	⬇️
src/hnsw/utils.c	81.08% <66.66%> (-6.92%)	⬇️

... and 1 file with indirect coverage changes