[Feature] Abstract Semantic Graph (ASG) - Base Implementation

[collinc97]

Motivation

The primary motivation is to provide a cleaner, safer, and faster way to implement compiler passes. The ASG provides this by representing Leo programs by semantics rather than syntax.

This PR merges the changes from asg-asg and asg-comments into the current master. Includes commits from #570 and #588.

Huge shoutout to @Protryon for the colossal amount of work here.

Changes

Here is a list of current compiler issues that the ASG is targeted to resolve:

• [Bug] Function can return variables defined inside if else scope. #377
• Strange behavior surrounding for loop #410
• [Bug] assigning mutable variable to mutable variable causes "no implementation" when used in math #449
• [Bug] Dependency of const vars on non-const vars is not rejected #514
• Can’t call functions with arrays as parameters directly: #522
• Comparison of multidimensional arrays with the same number of elements is incorrect. #534
• [Bug]As a parameter, a function can be called both static and as an instance function. #543
• [Bug]The same name is successfully duplicated and, depending on the context, points to different objects #546
• [Bug] Import usage in circuit functions #557
• [Bug] cannot access the index of non-array type #559
• [Bug] using array tuple syntax in input produces wrong array shape #563
• [Bug] input array len not enforced #564

[codecov]

Codecov Report

Merging #594 (aa01421) into master (2849a27) will increase coverage by 1.50%.
The diff coverage is 74.19%.

@@            Coverage Diff             @@
##           master     #594      +/-   ##
==========================================
+ Coverage   74.95%   76.45%   +1.50%     
==========================================
  Files         477      571      +94     
  Lines       14031    19062    +5031     
==========================================
+ Hits        10517    14574    +4057     
- Misses       3514     4488     +974     

Impacted Files	Coverage Δ
asg/src/const_value.rs	38.62% <38.62%> (ø)
asg/src/expression/binary.rs	39.35% <39.35%> (ø)
asg/src/statement/expression.rs	41.17% <41.17%> (ø)
asg/src/expression/tuple_access.rs	45.28% <45.28%> (ø)
asg/src/expression/array_range_access.rs	46.90% <46.90%> (ø)
asg/src/expression/unary.rs	47.05% <47.05%> (ø)
asg/src/expression/tuple_init.rs	48.48% <48.48%> (ø)
asg/src/expression/circuit_access.rs	49.61% <49.61%> (ø)
asg/src/expression/array_access.rs	52.17% <52.17%> (ø)
asg/src/expression/ternary.rs	52.27% <52.27%> (ø)
... and 187 more

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