Add fuzz seeds for sqlite variable tokens

Author: LucaCappelletti94

fuzz/fuzz_seeds/sqlite_2559_variable_tokens.sql

@@ -0,0 +1,2 @@
+SELECT #a, @2t, :9c, @a$, :a(x), @a(), :::6, :a::b, $a::b, @::b, #::b, ($$::), @é, :é, #é, :::é;
+SELECT a FROM t WHERE b = :c;