fix(bval): Handle trailing whitespace without newlines

[effigies]

Fixes #9, adds a test that fails thus (if we revert the second commit):

Test bval/bvec parsing ... Load 3 bvals - missing newline => ./src/files/dwi.test.ts:10:11
error: AssertionError: Values are not equal.


    [Diff] Actual / Expected


    [
      [
        "0",
        "1",
        "2",
-       "",
      ],
    ]

  throw new AssertionError(message);
        ^
    at assertEquals (https://jsr.io/@std/assert/1.0.7/equals.ts:51:9)
    at file:///home/chris/Projects/bids/validator/src/files/dwi.test.ts:12:5
    at innerWrapped (ext:cli/40_test.js:191:11)
    at exitSanitizer (ext:cli/40_test.js:107:33)
    at Object.outerWrapped [as fn] (ext:cli/40_test.js:134:20)
    at TestContext.step (ext:cli/40_test.js:492:37)
    at file:///home/chris/Projects/bids/validator/src/files/dwi.test.ts:10:11

Test bval/bvec parsing ... Load 3 bvals - missing newline => ./src/files/dwi.test.ts:22:11
error: AssertionError: Values are not equal.


    [Diff] Actual / Expected


    [
      [
        "0",
        "1",
        "2",
      ],
      [
        "0",
        "1",
        "2",
      ],
      [
        "0",
        "1",
        "2",
-       "",
      ],
    ]

  throw new AssertionError(message);
        ^
    at assertEquals (https://jsr.io/@std/assert/1.0.7/equals.ts:51:9)
    at file:///home/chris/Projects/bids/validator/src/files/dwi.test.ts:24:5
    at innerWrapped (ext:cli/40_test.js:191:11)
    at exitSanitizer (ext:cli/40_test.js:107:33)
    at Object.outerWrapped [as fn] (ext:cli/40_test.js:134:20)
    at TestContext.step (ext:cli/40_test.js:492:37)
    at file:///home/chris/Projects/bids/validator/src/files/dwi.test.ts:22:11

 FAILURES

Test bval/bvec parsing ... Load 3 bvals - missing newline => ./src/files/dwi.test.ts:10:11
Test bval/bvec parsing ... Load 3 bvals - missing newline => ./src/files/dwi.test.ts:22:11

FAILED | 47 passed (652 steps) | 1 failed (2 steps) (21s)

error: Test failed