Improve testing bracketed symbols

Also test EQU and _RS constants, as well as that EQUS errors out,
and that labels don't work.

test/asm/bracketed-symbols.out.pipe

@@ -1,5 +1,12 @@
+ERROR: -(16):
+    Print types are only allowed for numbers
+ERROR: -(20):
+    Expression must have a constant value
 $2A
 2a
 2A
 42
 101010
+10100111001
+0
+You can't format me!