Insert raw definition into .smt2 file with #![raw_definie()] attribute

[coeff-aij]

This attribute allows users to inject arbitrary string literals directly into the generated .smt2 files using crate-level inner attributes.

• Usage
  By adding an inner attribute to the crate root, such as:

#![feature(custom_inner_attributes)]
#![thrust::raw_define("(define-fun is_double ((x Int) (doubled_x Int)) Bool
    (=
        (* x 2)
        doubled_x
    )
)")]

// -- snip --

The attached string literal will be inserted into the head of the generated SMT-LIB2 file:

(set-logic HORN)

(define-fun is_double ((x Int) (doubled_x Int)) Bool
    (=
        (* x 2)
        doubled_x
    )
)

; -- snip --

• Motivation
  This feature is intended for debugging and testing. It enables the manual injection of SMT-LIB logic, serving as a workaround until a dedicated parser is implemented.

[coeff-aij]

Probably I have to add some more tests and documentation comments.

[coeff-aij]

How can I test that the Thrust panics with a specific error message? I tried using //@error-in-other-file, but I might be misunderstanding its purpose.

[coeff-aij]

parseg_raw_definition() is implemented on annot::AnnotParser and it's new() requires any Resolver instance, which isn't actually used in parsing of raw definitions.
I might have to fix so that no Resolver is required for this analysis.