Fetch int-64 values from h5grove as binary to maintain precision

[axelboc]

Follows #1745 and closes #1679

[loichuder]

Why not returning BigInt64Array here ?

[axelboc]

Sorry, should have explained: for the same reason I have a separate type union, a separate type guard, etc. — when both kinds of typed arrays are mixed together in a union, TypeScript goes wild:

• You can't invoke the Big(U)Int64Array constructors with number[], only with bigint[] (so new IntOrBigIntTypedArray(arr as number [] | bigint[]) doesn't type-check)
• You can't loop through the array, since number[] and bigint[] aren't compatible.

Having a single function worked fine in h5grove-api since we invoke the typed array constructor with a buffer. However, it failed in useIgnoreFillValue, where we pass a number[]:

  const DTypedArray = typedArrayFromDType(dataset.type);

  // Cast fillValue in the type of the dataset values to be able to use `===` for the comparison
  const fillValue =
    DTypedArray && typeof wrappedFillValue[0] === 'number'
      ? new DTypedArray(wrappedFillValue as number[])[0]
      : undefined;

Arguably, perhaps useIgnoreValue should be reworked to support bigints as well... Seemed like a can of worms, though, so I went with a compromise.

[loichuder]

Yeah, ok I see.