Provide CLI feedback for plug-in installation

[infotexture]

Description

The dita --install option currently provides no confirmation when plug-ins are successfully installed (or removed).

This is consistent with the typical "no news is good news" approach for basic UNIX utilities, and tolerable enough when installing or removing a single plug-in.

However, the current behavior is less helpful in situations when the plugins directory is manually modified to add/remove multiple plug-ins at once, or install multiple plug-ins from a single .zip file.

Possible Solution

Since DITA-OT maintains a list of currently installed plug-ins and updates this configuration during the integration process, it would be helpful to compare the before/after states and print a summary to the console upon completion, for example:

$ dita --install
+ Installed com.example.plugin1
- Removed com.example.plugin2

It might also be useful to conclude the integration process by printing the current list of available plug-ins to the console via the dita --plugins option.

Since the plug-in registry changes for #3028 also permit the installation of plug-ins by alias, this would also serve to confirm the user's intent by displaying the plug-in ID that was actually installed via the alias.

This would be more consistent with the feedback provided by other CLI-based package managers.

(See related enhancement #3070).

[jelovirt]

install multiple plug-ins from a single .zip file

Does that work? 🤔

[infotexture]

My recollection was that multiple plug-ins could be installed simultaneously by passing a .zip file that contained several plug-ins, each in top-level folders of the archive.

But I tested now, and only 1 of the 4 plug-ins in the archive was installed (first in alphabetical order).

@robander Did I dream this, or did it used to work that way?

Having to unpack the archive to the plugins folder first seems like an unnecessary step.

[robander]

I think I've asked about this in the past but it was never supported - like @jelovirt I was a bit surprised by that in the initial report. It came up for me when first working with some of the D4P and SVG Diagram support, each of which required a bundle of plugins to work. I think I asked about that at the time and it was clearly out of scope for the initial dita --install support, but I hadn't thought about it since.

[infotexture]

Resolved in #3110 & a17143c.