feat: replace new keyword with this constructor syntax and ClassName.new() calls across core library and docs

Replace all uses of the `new` reserved word with explicit `this new()` constructor definitions and `ClassName.new()` instantiation calls in builtin/core.wren. Update all documentation files (classes.markdown, fiber.markdown, fn.markdown, sequence.markdown, error-handling.markdown, expressions.markdown, fibers.markdown, functions.markdown) to reflect the new constructor syntax, removing `new` keyword examples and replacing them with `ClassName.new()` patterns and `this new()` definitions.

test/language/method/arity.wren

@@ -19,7 +19,7 @@ class Foo {
   method(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p) { a + b + c + d + e + f + g + h + i + j + k + l + m + n + o + p}
 }
 
-var foo = new Foo
+var foo = Foo.new()
 IO.print(foo.method) // expect: getter
 IO.print(foo.method()) // expect: no args
 IO.print(foo.method(1)) // expect: 1

test/language/method/empty_block.wren

@@ -2,4 +2,4 @@ class Foo {
   bar {}
 }
 
-IO.print((new Foo).bar) // expect: null
+IO.print(Foo.new().bar) // expect: null

test/language/method/long_name.wren

@@ -4,4 +4,4 @@ class Foo {
   }
 }
 
-IO.print((new Foo).thisHasAMethodNameThatIsExactly64CharactersLongWhichIsTheMaximum) // expect: result
+IO.print(Foo.new().thisHasAMethodNameThatIsExactly64CharactersLongWhichIsTheMaximum) // expect: result

test/language/method/many_methods.wren

@@ -1010,7 +1010,7 @@ class Foo {
   method999 { 1 }
 }
 
-var foo = new Foo
+var foo = Foo.new()
 var result = 0
 result = result + foo.method000
 result = result + foo.method001

test/language/method/newlines.wren

@@ -3,7 +3,7 @@ class Foo {
   [a, b] { "subscript " + a + " " + b }
 }
 
-var foo = new Foo
+var foo = Foo.new()
 
 // Allow newlines after commas and before ")".
 IO.print(foo.method("a",

test/language/method/not_found.wren

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

test/language/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 'someUnknownMethod(_,_,_,_,_,_,_,_,_,_,_)'.
+Foo.new().someUnknownMethod(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11) // expect runtime error: Foo does not implement 'someUnknownMethod(_,_,_,_,_,_,_,_,_,_,_)'.

test/language/method/not_found_multiple_arguments.wren

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

test/language/method/not_found_one_argument.wren

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

test/language/method/operators.wren

@@ -18,7 +18,7 @@ class Foo {
   - { "prefix -" }
 }
 
-var foo = new Foo
+var foo = Foo.new()
 IO.print(foo + "a") // expect: infix + a
 IO.print(foo - "a") // expect: infix - a
 IO.print(foo * "a") // expect: infix * a

test/language/method/static.wren

@@ -6,7 +6,7 @@ class Foo {
   static bar(arg) { "on metaclass " + arg }
 }
 
-IO.print((new Foo).bar)        // expect: on instance
+IO.print(Foo.new().bar)        // expect: on instance
 IO.print(Foo.bar)              // expect: on metaclass
-IO.print((new Foo).bar("arg")) // expect: on instance arg
+IO.print(Foo.new().bar("arg")) // expect: on instance arg
 IO.print(Foo.bar("arg"))       // expect: on metaclass arg

test/language/method/subscript_operators.wren

@@ -7,7 +7,7 @@ class Foo {
   [a, b, c]=(value) { "3-subscript setter " + a + " " + b + " " + c + " = " + value }
 }
 
-var foo = new Foo
+var foo = Foo.new()
 IO.print(foo["a"]) // expect: 1-subscript a
 IO.print(foo["a", "b"]) // expect: 2-subscript a b
 IO.print(foo["a", "b", "c"]) // expect: 3-subscript a b c