Verilog: consolidate assignment-related tests in one directory

Author: kroening

regression/verilog/assignment-to-concatenation/test.desc renamed to regression/verilog/assignments/assignment-to-concatenation1.desc

@@ -1,5 +1,5 @@
 CORE broken-smt-backend
-main.v
+assignment-to-concatenation1.v
 --bound 1
 ^EXIT=0$
 ^SIGNAL=0$

regression/verilog/assignment-to-concatenation/main.v renamed to regression/verilog/assignments/assignment-to-concatenation1.v

@@ -1,5 +1,5 @@
 CORE broken-smt-backend
-main.v
+assignment-to-index1.v
 --bound 1
 ^EXIT=0$
 ^SIGNAL=0$

regression/verilog/assignment-to-range1/test.desc renamed to regression/verilog/assignments/assignment-to-index1.desc

@@ -1,5 +1,5 @@
 KNOWNBUG
-main.sv
+assignment-with-function-call1.sv
 --bound 1
 ^EXIT=0$
 ^SIGNAL=0$