Custom Tools / SDK: Allow specifying the tool category icon

[mkhtran]

When a plugin is created, it can be labelled with any tool category, existent or non-existent. If the category does not exist, Designer will create it and give it a default icon. It would be nice if a category icon could also be specified, specifically for this case.

Specifying a tool category icon

Developers would have a way to (optionally) specify the tool category icon for their plugin. This would likely be part of `ayx_workspace.json`.

{
  "name": "My Plugin",
  "tool_category": "Custom Category",
  "tool_category_icon_path": "configuration\\tool_category_icon.png",
  "package_icon_path": "configuration\\package_icon.png",
  ...
}

Behavior when installing a plugin

If a plugin has a tool category icon specified, Designer should do the following when installing the plugin:

• If the tool category already exists and has an icon, no changes are made
• If the tool category already exists and does not have an icon set, the category is updated with the specified icon
• If the tool category does not exist, the category is made and its icon is set to the specified icon

This prevents changing the icons of existing categories (including built-in categories), but would prevent subsequent plugin versions from updating their tool category icons.

Use case

The company Acme Corporation develops a plugin for interfacing with Acme-related products, and would like all its tools to be grouped in a new category called "Acme" whose icon is the Acme icon.