This brings back many of the changes in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/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 https://gitlab.com/gitlab-org/gitlab/-/issues/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.