From ember-template-lint documentation (https://github.com/ember-template-lint/ember-template-lint/blob/master/docs/rule/no-unbound.md):
```
{{unbound}} is a legacy hold over from the days in which Ember's template engine was less performant. Its use today is vestigial, and it no longer offers performance benefits.
It is also a poor practice to use it for rendering only the initial value of a property that may later change.
```
Co-Authored-By: Jarek Radosz <jradosz@gmail.com>
* FEATURE: ability to add all active components to theme
* FIX: add a component to all themes takes only active ones
* FIX: move select components/themes to top
* FIX: improve defaultIsAvailable
* FIX: Add filter(Boolean) and remove btn class
* FEATURE: Ability to add components to all themes
This is the first and functional step from that topic https://dev.discourse.org/t/adding-a-theme-component-is-too-much-work/15398/16
The idea here is that when a new component is added, the user can easily assign it to all themes (parents).
To achieve that, I needed to change a site-setting component to accept `setDefaultValues` action and `setDefaultValuesLabel` translated label.
Also, I needed to add `allowAny` option to disable that for theme selector.
I also refactored backend to accept both parent and child ids with one method to avoid duplication (Renamed `add_child_theme!` to more general `add_relative_theme!`)
* FIX: Improvement after code review
* FIX: Improvement after code review2
* FIX: use mapBy and filterBy directly
