[stdlib] Add a bunch of new features to object (dict, tuple, __iter__, structs!)

[rd4com]

Hello, it would be really nice to use our object a lot more,
it is the default type in def functions and makes programming easy,
hope this pr is good, it has a dict implementation for both K and V of object,
really looking forward to use the features of the pr everyday:

• simplify a lot by removing structs that wrapped other structs
  uses Arc in in variant for ref count (list, dict, attributes, string)
• add dict and tuple with ref count ❤️‍🔥
• implement repr for RefCountDict and RefCountTuple
• add hash for Self
• implement eq for RefCountAttrsDict, RefCountDict and RefCountTuple
• add _ObjectImpl.ref_count() for RefCounted* structs
• add contains for list, dict and tuple
• add WrappedStruct
• add pop for list and dict
• add len for dict and tuple
• add int("1") conversion to int
• str(x) returns "value" instead of " 'value' "
• add object(List(Attr("values",[1, 2])))

Can anybody check a benchmark for the matmul example ?
because changes might be slower or faster (not tested)

With this that now works:

    a = object.dict()
    a["one"] = 1
    a[2] = "two"
    assert_equal(a["one"], 1)
    assert_equal(a[2], "two")

We can then implement type(x) is type(y) !
json could also be an exciting next step,
then we could have a hybrid between dynamic and typed:
a.typed[Int]() += SIMD[Int, 4]().reduce_add()

Hope you like this pr, if it's not good enough no worries lol
(no merge 👍 or we could even refine with huge reviews if needed)

usecase is to transition from
def event(inout self, props: PythonObject)
to
def event(inout self, props)
in a web-framework i'm trying to create

[martinvuyk]

Hi @rd4com this looks good. Left some nitpicks on the usages of dunders that can be changed to builtin functions.

[rd4com]

Hello @JoeLoser , last review is implemented !
Note that with this draft that uses ref, users can do:

my_list._value.get_as_list()[x._value.get_as_int()]._value.get_as_list()[y._value.get_as_int()] = z
#List.__getitem__[0]().__getitem__[1]() = z

# edit: with latest commits
my_list.as_list()[x.as_int()].as_list()[y.as_int()] = z

It is super important, because the lifetime/origin is propagated through,
list, dict, tuple, attrdict, are implemented as List[object],Dict.., so we can enjoy a ref to an object !
We might need our arc to share the PythonObject ref_count so objects can live in both world at the same time,
and the mojo side would be able to use a ref to an arc innervalue 👍
(ping to @ConnorGray )

Last commit also have __iter__ for both list and dict keys ❤️‍🔥
(it works by storing the iterator in a variant)