feat: add forceSelect collection / global config property

[r1tsuu]

What?

Adds a new property to collection / global config forceSelect which can be used to ensure that some fields are always selected, regardless of the select query.

Why?

This can be beneficial for hooks and access control, for example imagine you need the value of data.slug in your hook.
With the following query it would be undefined:
?select[title]=true
Now, to solve this you can specify

forceSelect: {
  slug: true
}

How?

Every operation now merges the incoming select with collectionConfig.forceSelect.