(#7285) Use Augeas NO_LOAD/incl to optimise loading based on context

When the context property is given, use the NO_LOAD flag to stop Augeas loading
all files for all lenses. Removes all /augeas/load//incl nodes where the glob
doesn't match the context given before loading.

This speeds up loading when the context is provided, as Augeas only reads and
parses relevant files, instead of every known file for each resource.

Requires Augeas 0.8.2 with the glob() path function call.