[Bug] [Compiler-v2] error messages are unclear

[brmataptos]

🐛 Bug

The v2 compiler is currently producing error messages like the following, which are technically true descriptions of conflicts in a set of type constraints describing the program, but are not intuitive to less expert developers. We should re-visit these error messages and see if they can be clarified. Fortunately, most of these are now tagged with "(from assignment context)".

third_party/move/move-compiler-v2/tests/checking/typing/bind_wrong_type.exp:

error: expected `()` but found `integer` (from assignment context)
   ┌─ tests/checking/typing/bind_wrong_type.move:12:13
   │
12 │         let () = 0;
   │             ^^

error: expected `()` but found `u64` (from assignment context)
   ┌─ tests/checking/typing/bind_wrong_type.move:19:13
   │
19 │         let (): u64 = ();
   │      

error: expected 4 item(s), found 3
   ┌─ tests/checking/typing/bind_wrong_type.move:20:47
   │
20 │         let (x, b, R{f}): (u64, bool, R, R) = (0, false, R{f: 0});
   │    

error: expected 4 item(s), found 3
   ┌─ tests/checking/typing/bind_wrong_type.move:20:13
   │
20 │         let (x, b, R{f}): (u64, bool, R, R) = (0, false, R{f: 0});
   │                                                    ^^^^^^^^^^^^^^^^^^^

[brmataptos]

To link back to the relevant PR, here: #9792