Added support for ordering halfvec and sparsevec columns

test/expected/btree.out

@@ -1,17 +0,0 @@
-SET enable_seqscan = off;
-CREATE TABLE t (val vector(3));
-INSERT INTO t (val) VALUES ('[0,0,0]'), ('[1,2,3]'), ('[1,1,1]'), (NULL);
-CREATE INDEX ON t (val);
-SELECT * FROM t WHERE val = '[1,2,3]';
-   val   
----------
- [1,2,3]
-(1 row)
-
-SELECT * FROM t ORDER BY val LIMIT 1;
-   val   
----------
- [0,0,0]
-(1 row)
-
-DROP TABLE t;