Implement TypeMap to enable module specific type map registration

[hanjinliu]

Closes #676

(I said WidgetStore in the issue but it turned out that there were more things to store so I simply named it TypeMap 🥲 )
All the functions that used the global type map before are now referring to the global instance of TypeMap.

Example:

from magicgui.type_map import TypeMap
from magicgui.widgets import Slider
from magicgui import magicgui

mymap = TypeMap()
mymap.register_type(int, widget_type=Slider)

@magicgui
def func(x: int): ...  # <- x is SpinBox, as usual

@mymap.magicgui
def func(x: int): ...  # <- x is Slider

Some functions, such as magicgui and create_widget, no longer need to be in the files they used to be, but they are still in the original files in case some users use private import such as from magicgui.type_map._magicgui import magicgui. Probably we need some refactoring in the future because there are some dirty import statements inside functions to avoid circular import.

[codecov]

Codecov Report

Attention: Patch coverage is 95.96774% with 10 lines in your changes missing coverage. Please review.

Project coverage is 89.07%. Comparing base (058d63c) to head (a562cff).

Files with missing lines	Patch %	Lines
src/magicgui/type_map/_type_map.py	95.96%	9 Missing ⚠️
src/magicgui/type_map/_magicgui.py	90.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #677      +/-   ##
==========================================
- Coverage   89.16%   89.07%   -0.10%     
==========================================
  Files          39       39              
  Lines        4746     4780      +34     
==========================================
+ Hits         4232     4258      +26     
- Misses        514      522       +8     

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[hanjinliu]

It seems pint has some problem with dataclass (see here).

[Czaki]

The current problem is caused by flexparser 0.4 release: hgrecco/flexparser#12

[hanjinliu]

Ah, that's why all the tests including python<3.13 are failing.