Add env variable parsing for SLDService

Description

A vector layer, or a mosaic, can be defined with a CQL filter based on enviroment variables.
Said variables then control the contents of the raster or vector, thus changing the results of the classification.
As a result, it's important to allow the specification of env variables in classification calls.

Environment

None

Assignee

Andrea Aime

Reporter

Andrea Aime

Triage

None

Fix versions

Affects versions

None

Components

Priority

Medium
Configure