Inconsistent tagging of slicing-related plugins

[jacopotediosi]

While searching plugins that implement OctoPrint's slicing functionality, I noticed that they are tagged inconsistently, which makes them harder to find.

Current state:

• PrePrintService: tags slic3r, slicing
• Slic3r: tag slic3r
• Full-featured Slicer: tag slicer
• CuraEngine Legacy: tag slicer

It would be useful to unify the tagging of slicing-related plugins (e.g. consistently using either slicer or slicing, what you prefer) in order to improve discoverability.

In addition, I noticed that a new plugin called InternalSlicer was recently created. In this forum discussion, I invited the maintainer to add it to this repository as well. We should also remember to make sure it has the correct tag once it is added.

[jneilliii]

added the slicer tag to the two that didn't have that in above PR. as for the unregistered plugin, I agree would be great to have that other one as well, but it's the plugin's maintainer that is responsible for registering their plugin, acknowledging the expected responsibilities of such.

[jacopotediosi]

Thanks!