error range includes leading trivia, instead of just the offending token

[Omar Tawfik]

Originally discovered in #840:

slang/crates/solidity/testing/snapshots/cst_output/TupleDeconstructionStatement/with_var/generated/0.5.0-failure.yml

Lines 9 to 16 in e89c46c

     Error: Expected OpenParen. 
        ╭─[crates/solidity/testing/snapshots/cst_output/TupleDeconstructionStatement/with_var/input.sol:1:1] 
        │ 
      1 │ ╭─▶ // "var" should be disabled in "0.5.0": 
      2 │ ├─▶ var (foo, bar) = rhs; 
        │ │                            
        │ ╰─────────────────────────── Error occurred here. 
     ───╯