Feature/api queries star share modal

https://www.openproject.org/work_packages/8227
@tilt is there?

You could also use [coercible](https://github.com/solnic/coercible), which we already have bundled (it's an indirect dependency of grape)

```ruby
coercer = Coercible::Coercer.new
coercer[String].to_boolean('true') # => true
coercer[String].to_boolean('0') # => false
```