Custom Tools / SDK: Allow localization of custom tools

[mkhtran]

All built-in tools have their names, descriptions, help URLs, etc. localized to the currently selected locale. Custom tools should also be able to do this.

Specify localized configuration values

Developers should have a way to specify localized values for any locales they choose to support. Similar to the deprecated .yxlang files, this can be done with supplementary `ayx_workspace.[locale].json` files that redefine a subset of configurations which support internationalization.

/* ayx_workspace.jp.json */
{
  "tools": {
    "MyCustomTool": {
      "configuration": {
        "long_name": "カスタムツール",
        "description": "これは日本語です",
        "help_url": "https://mywebsite.com/help/jp/my-custom-tool"
      }
    }
  }
}