Move processes to 'proposals' (state of implementations)

[m-mohr]

Using the Hub, I made an overview of the processes not yet implemented at back-ends:

• aggregate_spatial_binary (marked as experimental anyway)
• aggregate_temporal_period (implemented as aggregate_temporal_frequency in GEE)
• cummax
• cummin
• cumproduct
• cumsum
• debug (planned to be implemented in GEE in the next weeks)
• filter_labels
• load_result
• load_uploaded_files
• reduce_dimension_binary (marked as experimental anyway)
• resample_cube_temporal (implemented once, but implementer reported issues resample_cube_temporal behavior #194)
• run_udf_externally (marked as experimental anyway)

I'm wondering whether we should move some or all of these into the new "proposals" folder until we have implementations that show the processes actually work as intended. Advantage would be that for proposals we actually allow "breaking changes" without PSC process as they are not part of the normative specification yet. That would allow more experiments in implementations for things we have not really practical experience with. (Of course this issue itself needs to go through the PSC.) Adding processes back is not a breaking change and doesn't necessarily need a PSC vote.

[m-mohr]

This is voted on by the PSC here: Open-EO/PSC#8

[m-mohr]

Approved by the PSC and implemented.