grammar checker settings should expose available pipelines

[snomos]

In the Divvun settings pane, in addition to the various errors one can (de)select, one should in addition be able to select the pipeline to run. This can be used to offer pipelines with other types of functionality, or targeted at other user groups (e.g. L2 vs L1). One could also differentiate the various pipelines as being public, beta, or closed, and have an option for displaying experimental (=beta) pipelines. Closed ones should never be available in the LO settings window (but can be tested on the command line).