Introduce Space, Dimensions, and GeneralDimensions

[ytdHuang]

Checklist

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• Please read Contributing to QuantumToolbox.jl.
• Any code changes were done in a way that does not break public API.
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Description

Summary of this PR:

New structures:

• AbstractSpace
• Space
• AbstractDimensions
• Dimensions
• GeneralDimensions

New field

• dimensions (originally called dims) for Qobj / QobjEvo / TimeEvolutionProblem / EigsolveResult

New property

• dims for Qobj / QobjEvo / TimeEvolutionProblem / EigsolveResult

New internal functions:

• get_dimensions_to
• get_dimensions_from
• dimensions_to_dims: transform AbstractDimensions to integer-vector
• _get_dims_string: to get the dims string for printing

Changed internal functions:

• _check_dims -> _gen_dimensions. This was the one to check the format of user specified dims, now it also checks the format and generates the Dimensions structure.
• check_dims -> check_dimensions. This was the one to check if the two Qobj have the same dims, now it allows multiple input Qobj and check whether all Qobj.dimensions are equal).

Related issues or PRs

close #271
close #353

[codecov]

Codecov Report

Attention: Patch coverage is 96.66667% with 9 lines in your changes missing coverage. Please review.

Project coverage is 93.15%. Comparing base (5b08c04) to head (e6166b8).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/qobj/dimensions.jl	92.10%	3 Missing ⚠️
src/qobj/arithmetic_and_attributes.jl	96.66%	2 Missing ⚠️
src/qobj/quantum_object_base.jl	94.44%	2 Missing ⚠️
src/qobj/quantum_object.jl	95.83%	1 Missing ⚠️
src/time_evolution/time_evolution.jl	88.88%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #360   +/-   ##
=======================================
  Coverage   93.14%   93.15%           
=======================================
  Files          41       43    +2     
  Lines        2684     2775   +91     
=======================================
+ Hits         2500     2585   +85     
- Misses        184      190    +6     

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