ast: improve the assert informations (related #22668)

[yuyi98]

This PR improve the assert informations (related #22668).

type Sum = int | string

fn main() {
   assert Sum(1) == Sum(2)
}

PS D:\Test\v\tt1> v run .
.\\tt1.v:4: FAIL: fn main.main: assert Sum(1) == Sum(2)
  left value: Sum(1)
  right value: Sum(2)
V panic: Assertion failed...
v hash: 9c72d94
C:/Users/yuyi9/AppData/Local/Temp/v_0/tt1.01JB994DG71BPHW0GK9AEFXYZS.tmp.c:7314: at _v_panic: Backtrace
C:/Users/yuyi9/AppData/Local/Temp/v_0/tt1.01JB994DG71BPHW0GK9AEFXYZS.tmp.c:13684: by main__main
C:/Users/yuyi9/AppData/Local/Temp/v_0/tt1.01JB994DG71BPHW0GK9AEFXYZS.tmp.c:13721: by wmain
00466ea8 : by ???
0046700b : by ???
7ffe207e259d : by ???

_{Huly®: V_0.6-21128}

[spytheman]

Excellent work.
Thank you for fixing the other cases as well 🙇🏻‍♂️ .