Add option to track order of attributes and fields

[bmaranville]

Enable "track order" mode of hdf5 for attributes of Dataset, and (fields and attributes) of Group. When track_order == true for a Group, both fields and attributes keep their insertion order on read. For a Dataset, the attributes keep their insertion order when the flag is set.

Note that the flag is not inherited, i.e. if an h5wasm.Group object is created with track_order = true, its sub-groups and contained Dataset objects will not have the flag enabled by default. The flag is added to the File constructor just to track order of immediate children of the root group.

Changes three signatures in the h5wasm API:

• h5wasm.File(filename: string, mode: ACCESS_MODESTRING = "r", track_order: boolean = false)
• h5wasm.Group.create_group(name: string, track_order: boolean = false)

• h5wasm.Group.create_dataset(args: {
    name: string,
    data: GuessableDataTypes,
    shape?: number[] | null,
    dtype?: string | null,
    maxshape?: (number | null)[] | null,
    chunks?: number[] | null,
    compression?: (number | 'gzip'),
    compression_opts?: number | number[],
    track_order?: boolean,
  })
  

Also adds one method to the Module API:

• open(filename: string, mode: number, track_order: boolean): bigint;

and modifies the signatures of three existing methods in the Module API:

• create_dataset
• create_group
• create_vlen_str_dataset

[bmaranville]

There is currently no way to determine if track_order has been set for an existing Group or Dataset in an HDF5 file - is that an important feature to add? It could be added to the metadata object (changing its interface) or it could be a separate on-demand query.

[bmaranville]

It seems like checking if order tracking is enabled in the creation property list is not an immediate need - I will merge this as-is shortly and make a new release.

[axelboc]

Module.open() is going to be super useful, thanks!

[axelboc]

Could H5F_ACC_RDONLY be the default for h5_mode?

[bmaranville]

sure!