Merge layout checks

[chronicl]

There is multiple places in shame where type layouts are checked and compared. It would be nice to merge these checks/comparisons as much as possible to reduce maintenance burden.

After #19 and #21 mainly

• src/frontend/any/rust_types/type_layout/construction.rs
• src/frontend/any/rust_types/type_layout/eq.rs

contain these checks and comparisons.

Suggested approach

Integrate check_repr_equivalence_for_type of construction.rs into check_eq of eq.rs by passing an EqContext enum, which describes in what kind of setting we are comparing the two type layouts. check_eq can keep it's simple type_layout1 == type_layout2 check and in case of a mismatch EqContext is passed to the LayoutMismatch error, which handles figuring out where exactly the mismatch occured and generates an error message appropriate for the EqContext.