Use more comprehensive signature strings for methods.

test/method/not_found.wren

@@ -1,3 +1,3 @@
 class Foo {}
 
-(new Foo).someUnknownMethod // expect runtime error: Foo does not implement method 'someUnknownMethod' with 0 arguments.
+(new Foo).someUnknownMethod // expect runtime error: Foo does not implement 'someUnknownMethod'.

test/method/not_found_eleven_arguments.wren

@@ -1,3 +1,3 @@
 class Foo {}
 
-(new Foo).someUnknownMethod(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11) // expect runtime error: Foo does not implement method 'someUnknownMethod' with 11 arguments.
+(new Foo).someUnknownMethod(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11) // expect runtime error: Foo does not implement 'someUnknownMethod(_,_,_,_,_,_,_,_,_,_,_)'.

test/method/not_found_multiple_arguments.wren

@@ -1,3 +1,3 @@
 class Foo {}
 
-(new Foo).someUnknownMethod(1, 2) // expect runtime error: Foo does not implement method 'someUnknownMethod' with 2 arguments.
+(new Foo).someUnknownMethod(1, 2) // expect runtime error: Foo does not implement 'someUnknownMethod(_,_)'.

test/method/not_found_one_argument.wren

@@ -1,3 +1,3 @@
 class Foo {}
 
-(new Foo).someUnknownMethod(1) // expect runtime error: Foo does not implement method 'someUnknownMethod' with 1 argument.
+(new Foo).someUnknownMethod(1) // expect runtime error: Foo does not implement 'someUnknownMethod(_)'.

test/method/static_method_not_found.wren

@@ -1,3 +1,3 @@
 class Foo {}
 
-Foo.bar // expect runtime error: Foo metaclass does not implement method 'bar' with 0 arguments.
+Foo.bar // expect runtime error: Foo metaclass does not implement 'bar'.