Support for terra rasters

[KyleLochhead]

Start the process of supporting terra

[KyleLochhead]

Removing pgGetRast()
The use of raster package in clus is predominately found in the dataLoaderCLUS module - which sets up the spatial aspects of data stored in a postgresql database. The main function for connecting postgresql raster objects with R is the rpostgis::pgGetRast() function. However, this function is mostly a wrapper for a DBI::dbGetQuery() call where the postgresql function st_dumpvalues() is used to stream all raster values into a table then into R. The proceeding steps of rpostgis::pgGetRast() build the raster using its metadata and then assign its values from this stream.

Proposed workaround

1. Run one query to fetch the raster metadata.
   select st_xmax(st_envelope(boo.rast)) as xmx,
   st_xmin(st_envelope(boo.rast)) as xmn,
   st_ymax(st_envelope(boo.rast)) as ymx,
   st_ymin(st_envelope(boo.rast)) as ymn,
   st_width(boo.rast) as cols,
   st_height(rast) as rows from (SELECT st_union(ST_Clip(foo.rast, 1, foo.wkb_geometry, true)) as rast FROM
   (SELECT st_union(rast) as rast, wkb_geometry from rast.bc_ha_slope, tsa_aac_bounds
   WHERE tsa_name = 'Quesnel_TSA' AND ST_Intersects(rast, wkb_geometry) group by wkb_geometry) as foo) boo;

2. All remaining querys simply stream raster values
   SELECT unnest(st_dumpvalues(st_union(ST_Clip(foo.rast, 1, foo.wkb_geometry, true)), 1)) as vals FROM
   (SELECT st_union(rast) as rast, wkb_geometry from rast.bc_ha_slope, tsa_aac_bounds
   WHERE tsa_name = 'Quesnel_TSA' AND ST_Intersects(rast, wkb_geometry) group by wkb_geometry) as foo

[KyleLochhead]

mock function for terra built need to test

[ElizabethKleynhans]

If rpostgis is updated to version 1.5.0 or greater the function RASTER_CLIP2 or any function that relies on pgGetRast will not work. This is because pgGetRast relies on rgeos and rgdal and both have been retired. We need to update the raster_clip functions to work around this issue.