refactor: Update handling of assigned attributes.

[norhan-synnada]

Description

Closes #216

What is Changed

• Data structures for storing assigned shapes, types and differentiabilities updated.
• Canonical inputs and outputs set by the user are traced also.
• Serialization for these attributes is updated.
• Setting strategy of these attributes updated in _add_connections method of BaseModel.
• trace flag added for _extend, extend and _add_connections methods.
• Dict conversions updated accordingly.
• Tests updated accordingly.

Checklist:

• Tests that cover the code added.
• Corresponding changes documented.
• All tests passed.
• The code linted and styled (pre-commit run --all-files has passed).

[codecov]

Codecov Report

Attention: Patch coverage is 94.00000% with 18 lines in your changes missing coverage. Please review.

Project coverage is 89.31%. Comparing base (ff34187) to head (061d53e).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
mithril/utils/dict_conversions.py	94.37%	9 Missing ⚠️
mithril/framework/logical/base.py	88.13%	7 Missing ⚠️
mithril/models/models.py	95.00%	2 Missing ⚠️

@@            Coverage Diff             @@
##             main     #220      +/-   ##
==========================================
- Coverage   89.37%   89.31%   -0.07%     
==========================================
  Files          75       75              
  Lines       17067    17203     +136     
==========================================
+ Hits        15254    15365     +111     
- Misses       1813     1838      +25     

Files with missing lines	Coverage Δ
mithril/cores/python/numpy/ops.py	81.40% <100.00%> (ø)
mithril/framework/common.py	96.67% <100.00%> (+0.02%)	⬆️
mithril/framework/logical/model.py	93.42% <100.00%> (ø)
mithril/framework/logical/operator.py	96.92% <100.00%> (ø)
mithril/framework/logical/operators.py	100.00% <100.00%> (ø)
mithril/framework/logical/primitive.py	96.00% <100.00%> (-4.00%)	⬇️
mithril/models/primitives.py	98.02% <100.00%> (ø)
mithril/models/models.py	90.14% <95.00%> (ø)
mithril/framework/logical/base.py	91.08% <88.13%> (-0.20%)	⬇️
mithril/utils/dict_conversions.py	81.89% <94.37%> (-0.46%)	⬇️

... and 3 files with indirect coverage changes

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[aturker-synnada]

LGTM