fix(parser): drop unused startPos in parseSnowflakeStageStatement, add LS test (#483)

Author: Ajit Pratap Singh

pkg/sql/parser/parser.go

@@ -779,8 +779,6 @@ func (p *Parser) parseSnowflakeUseStatement() (ast.Statement, error) {
 // ';' or EOF and returned as a DescribeStatement placeholder tagged with the
 // operation kind. No AST modeling yet; follow-up work.
 func (p *Parser) parseSnowflakeStageStatement(kind string) (ast.Statement, error) {
-	startPos := p.currentLocation()
-	_ = startPos
 	p.advance() // Consume leading kind token
 
 	// COPY INTO: consume the INTO keyword if present.

pkg/sql/parser/snowflake_stage_ops_test.go

@@ -28,6 +28,8 @@ func TestSnowflakeStageOps(t *testing.T) {
 		"list_stage": `LIST @my_stage`,
 
 		"remove_from_stage": `REMOVE @my_stage/old_files`,
+
+		"ls_alias": `LS @my_stage`,
 	}
 	for name, q := range queries {
 		q := q