v: utilize new diff functions p1

[ttytm]

Regarding the utilization of the new diff functions.

Currently, printing diffs has different approaches in the code base. Below I'm pointing out the two with major differences.

This is because when integrating the new diff functions, things can also be improved and made more consistent. So this PR should allow us to decide on one version that might be more suited then the other. Then it could serve as preferred way when updating the new diff functions in other places. I hope that going about it like this will help to create more clarity and simplify subsequent changes.

• Approach 1. (visible in the updated vlib/v/compiler_errors_test.v)
  Prints diffs OR expected and found.

• Approach 2. (visible in the old diff of slow_tests/inout/compiler_test.v)
  Prints first expected then found AND then differences. This is currently used more frequently.

  Atm. the PR updates slow_tests/inout/compiler_test.v from A2 to A1. Resulting in:

  Current	Updated

[JalonSolov]

Personally, I prefer brevity. If everything expected was found, why waste time/space reporting the 2 lists?

Perhaps it is useful sometimes. For those times, a verbose option would be handy, but I don't like verbosity as the default.

[ttytm]

@JalonSolov I'm in the same boat. When the expected and found are plainly printed, it's easy to lose track. Especially when they get longer.

Having it less verbose and straight to the point when there is a working diff tool should help to spot what is important more quickly.