[fine] Tests for conditional, semicolon optional at end of block

Just like rust, ';' means "discard this value".

fine/tests/expression/conditional.fine

@@ -0,0 +1,26 @@
+// concrete:
+// | File
+// |   IfStatement
+// |     ConditionalExpression
+// |       If:'"if"'
+// |       LiteralExpression
+// |         True:'"true"'
+// |       Block
+// |         LeftBrace:'"{"'
+// |         ExpressionStatement
+// |           LiteralExpression
+// |             String:'"\"discarded\""'
+// |           Semicolon:'";"'
+// |         ExpressionStatement
+// |           LiteralExpression
+// |             Number:'"23"'
+// |         RightBrace:'"}"'
+// |       Else:'"else"'
+// |       Block
+// |         LeftBrace:'"{"'
+// |         ExpressionStatement
+// |           LiteralExpression
+// |             Number:'"45"'
+// |         RightBrace:'"}"'
+//
+if true { "discarded"; 23 } else { 45 }