Priority is not respected between different callback types

[Carifio24]

Describe the bug
Priority is not respected between the different callback types (e.g. one-argument vs. two-argument callbacks). While priority is respected within each callback type, a one-argument callback is always called before a two-argument callback, regardless of priority.

To Reproduce
Here's an example script to demonstrate this issue. Run this, and you should see the one-argument callback get run first each time test.x is updated, despite the higher priority of the two-argument callback

from echo import add_callback, CallbackProperty

class Test:
    x = CallbackProperty(0)

test = Test()

def cb_onearg(value):
    print(f"cb_onearg called with {value}")

def cb_twoarg(old, new):
    print(f"cb_twoarg called with old: {old}, new: {new}")


add_callback(test, "x", cb_onearg, priority=1)
add_callback(test, "x", cb_twoarg, echo_old=True, priority=1000)


test.x = 2
test.x = 7

Expected behavior
I would expect the priority to be respected across all callbacks.

Details:

• Operating System: Ubuntu 22.04
• Python version: Python 3.11.5
• Echo version: 0.11
• How you installed: pip

Additional context
I think the issue comes from here, where we iterate over the callback containers separately. I haven't had a chance to look into this too much yet, but I guess rather than using the iterator, we could use each container's callbacks member (this includes the priority, the iterator does not) and then re-sort ourselves inside of notify.