Create process graphs for "alias" processes

[m-mohr]

Based on Open-EO/openeo-api#161 / Open-EO/openeo-api#256: Create process graphs for "alias" processes (neq, ndvi, ...).

[m-mohr]

• absolute
• add
• and
• array_contains
• between
• clip
• exp
• gte
• linear_scale_range
• ln
• lte
• multiply
• neq
• normalized_difference
• or
• sd
• sgn
• sort
• sqrt
• variance
• xor
• ceil/floor/int? Couldn't find a good "alternative"
• ~filter_bbox? (filter_geometry but CRS?) ~ Don't have a good way to emulate CRS
• first? (array_element(data, 0)), ignore_nodata with array_find Skipping for now due to the relatively intuitive way of emulating it
• last? (array_element / count), ignore_nodata with array_find Skipping for now due to the relatively intuitive way of emulating it
• mean? (sum / count)
• median?
• mod?
• round?
• sin/cos/tan/...? - I guess we can assume that if one of them is available, all of them are available?!
• variance/sd without referring to each other?