feat(validation): Assignment suggestions for = operator

[volsa]

This PR adds a validation to identify binary expressions using the = operator with no effects. For example the following statement foo = bar; does nothing and the user probably meant to use a := here, i.e. foo := bar;.

Resolves #939

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (a3c0055) 95.72% compared to head (5868db1) 95.74%.

Files	Patch %	Lines
src/resolver.rs	98.73%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1049      +/-   ##
==========================================
+ Coverage   95.72%   95.74%   +0.01%     
==========================================
  Files         153      153              
  Lines       42883    42875       -8     
==========================================
- Hits        41051    41049       -2     
+ Misses       1832     1826       -6     

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[ghaith]

How did these tests change? Nothing in the commit affects codegen/debugging

[volsa]

Adding a type-hint onto the condition of control statements does because we then enter the cast_if_needed here afaik

rusty/src/codegen/generators/expression_generator.rs

Line 182 in 1e88fe5

Ok(cast_if_needed!(self, target_type, actual_type, v, self.annotations.get(expression)))

[mhasel]

My guess is because the condition expressions now receive a type-hint, we hit the cast_if_needed call in generate_expression were previously we returned the value as-is

[volsa]

Just to add some additional context, this issue will go away once we implement #1041

[volsa]

Anything blocking this PR @ghaith @mhasel ? Arguably the IR got uglier but at the top of my head I'm not sure how else to implement this feature without type-hints.