GeoZarr - Support spectral bands as a dimension

Scope Feature request for the GeoZarr extension introduced recently (see PR #17362).

Description The GeoZarr example provided by @ahocevar demonstrates rendering a Zarr store compliant with the EOPF GeoZarr specification, which currently assumes that spectral bands are stored as separate Zarr array variables.

However, other product formats - such as ESA EOF-EOS - may instead encode spectral bands as a dedicated dimension within a multi-band array. This approach provides several advantages, including:

• more natural vectorized cross-band operations (and better performances),
• fewer objects in object storage,
• cleaner support for multiple multi-band variables within the same group.

This is also an open discussion within the EOPF community (see discussion #521).

While developing an extension for an OGC API Tiles implementation, support for both layouts was feasible.

Is this representation already supported by the current GeoZarr extension? If not, would support for band-as-dimension encoding be considered?

BONUS question: More generally, how does it support non-spatial dimension ? Can we specify a value for the time dimension (or altitude, etc.) ?

Thank you for your feedback.