Prohibit combined unary operators

[kaankacar]

Prohibit combined unary operators

• Add semantic error for chained/unparenthesized unary combinations (including parenthesized and negative-literal operands).
• Update unary/coverage tests to expect errors for sequences like --x, -~x, !!x.

Fixes #82

[0xGeorgii]

@kaankacar Thanks for the contribution. I think that because this check is scope-bounded and not actually a type-check, rather a semantic check, it makes sense to create a new core crate semantic-analysis so the high-level data flow should be like:

parse -> type check -> semantic check -> codegen ...

And there is actually a placeholder function for invoking this new crate:

https://github.com/Inferara/inference/blob/main/core/inference/src/lib.rs#L330

Also, how about parenthesized expressions such as -(~x)) etc.

Since we need to have 3 categories of reporting (info, warning, error), this should also be properly sorted out