api.rb

This brings back many of the changes in
!27276. This was
reverted due to some failures in the QA tests with nil parameters.

Grape v1.3.3 brings in Ruby 2.7 support and a number of fixes:
https://github.com/ruby-grape/grape/blob/master/CHANGELOG.md

1. Move all inherited `Grape::API` -> `Grape::API::Instance`
2. Remove use of Virtus since this has been removed from Grape.
3. Extract `Rack::Response` from API error
4. Grape v1.2.3 pulled in a fix used in `SafeFile`:
https://github.com/ruby-grape/grape/pull/1844, so we no longer need
to maintain our custom type.
5. Adapt `WorkhorseFile` with the latest changes to make custom types
work with Grape and dry-types.
6. Ensure `Array[String]` is coerced properly.

The change from Virtus to dry-types now requires all strings to be
coerced to arrays. Before this was done within Virtus.

7. Coerce `Array[Integer]` types to arrays of integers

8. Use a new helper, `coerce_nil_params_to_array!`, that coerces nil
Array inputs to empty arrays to preserve previous behavior.

If you have a parameter of type `Array[String]`, for example, Grape used
to coerce a provided `nil` value to `[]`. Grape no longer does this for
us, so we need a helper method that will automatically do this if the
parameter is present.

This merge request also introduces two Rubocop rules for Grape v1.3:

1. `Grape::API::Instance` instead of `Grape::API` is required, unless we
solve #215230.

2. Grape parameters defined with `Array` types (e.g. `Array[String]`,
`Array[Integer]`) must have a `coerce_with` block or they will fail to
parse properly. See
https://github.com/ruby-grape/grape/blob/master/UPGRADING.md for more
details.