Assertion comparator functions can be streamlined

[TheRealOwenRees]

We can eliminate the redundancy between our string and integer comparators by implementing a polymorphic type assertion. This allows a single function to handle any type safely by ensuring both operands share the same type identity.

export const assertEqual = `let assertEqual = (~message=?, a: 'a, b: 'a) => assertion(~message?, ~operator="assertEqual", (a, b) => a == b, a, b)`;

To tackle after Acronym is merged.

[BNAndras]

Something I've been wondering about is whether we should instead define these functions as valid ReScript code in our library. The test generator can pull out the source code from the library for a requested function and embed it in the test suite, and that'll let us make sure there aren't any issues in the functions ahead of time like typos.

[TheRealOwenRees]

In theory this would be the optimal solution. I am not sure how best to pull ReScript code into JS. My thinking would be that the test generator would be rewritten in ReScript