feat: implement setter syntax and assignment in named method calls

Add support for setter methods in the compiler by detecting '=' after a method name in namedCall, compiling the assigned value, and emitting the setter instruction. Includes new test cases for instance setters, static setters, assignment associativity, grouping, operator precedence errors, setter result values, and same-name getter/setter methods. Also updates the super call test with a TODO for super setter calls.

test/setter/associativity.wren

@@ -0,0 +1,18 @@
+class Foo {
+  new(value) { _value = value }
+  toString { return _value }
+  bar = value {
+    _value = value
+    return value
+  }
+}
+
+var a = new Foo("a")
+var b = new Foo("b")
+var c = new Foo("c")
+
+// Assignment is right-associative.
+a.bar = b.bar = c.bar = "d"
+io.write(a.toString) // expect: d
+io.write(b.toString) // expect: d
+io.write(c.toString) // expect: d

test/setter/grouping.wren

@@ -0,0 +1,6 @@
+class Foo {
+  bar = value { return value }
+}
+
+var foo = new Foo
+(foo.bar) = "value" // expect error

test/setter/infix_operator.wren

@@ -0,0 +1,6 @@
+class Foo {
+  bar = value { return value }
+}
+
+var foo = new Foo
+"a" + foo.bar = "value" // expect error

test/setter/instance.wren

@@ -0,0 +1,8 @@
+class Foo {
+  bar = value {
+    io.write(value)
+  }
+}
+
+var foo = new Foo
+foo.bar = "value" // expect: value

test/setter/is.wren

@@ -0,0 +1,6 @@
+class Foo {
+  bar = value { return value }
+}
+
+var foo = new Foo
+a is foo.bar = "value" // expect error

test/setter/prefix_operator.wren

@@ -0,0 +1,6 @@
+class Foo {
+  bar = value { return value }
+}
+
+var foo = new Foo
+!foo.bar = "value" // expect error

test/setter/result.wren

@@ -0,0 +1,6 @@
+class Foo {
+  bar = value { return "result" }
+}
+
+var foo = new Foo
+io.write(foo.bar = "value") // expect: result

test/setter/same_name_as_method.wren

@@ -0,0 +1,8 @@
+class Foo {
+  bar = value { io.write("set") }
+  bar { io.write("get") }
+}
+
+var foo = new Foo
+foo.bar = "value" // expect: set
+foo.bar // expect: get

test/setter/static.wren

@@ -0,0 +1,7 @@
+class Foo {
+  static bar = value {
+    io.write(value)
+  }
+}
+
+Foo.bar = "value" // expect: value