missing and wrong funcs:agg*

[VladimirAlexiev]

https://opengeospatial.github.io/ogc-geosparql/geosparql11/spec.html#_spatial_aggregate_functions defines 6 aggregation functions

Req 45 Implementations shall support geof:aggBoundingBox, geof:aggBoundingCircle, geof:aggCentroid, geof:aggConcaveHull, geof:aggConvexHull and geof:aggUnion as a SPARQL extension functions.

However, https://opengeospatial.github.io/ogc-geosparql/geosparql11/functions.ttl defines only 4, and the first 2 have wrong capitalization:

    101:funcs:aggboundingBox
    113:funcs:aggboundingCircle
    276:funcs:aggConcaveHull
    288:funcs:aggUnion

The respective collection mentions 5 (geof:aggConvexHull is missing):

funcs:sa
    a skos:Collection ;
    skos:definition "All the GeoSPARQL aggregation functions"@en ;
    skos:member
        funcs:aggBoundingBox ,
        funcs:aggBoundingCircle ,
        funcs:aggCentroid ,
        funcs:aggConcaveHull ,
        funcs:aggUnion ;