feat: toggle sortable arrays and blocks (beta)

[kendelljoseph]

Description

Given arrays and Blocks can be sorted by admins, sorting should be able to be toggled in the config

Example

Fields: Array, Blocks

const Field: CollectionConfig = {
  admin: {
    disableSortable: true
  }
}

Type of change

• [x] New feature (non-breaking change which adds functionality)
• [x] This change requires a documentation update

Checklist:

• [x] Existing test suite passes locally with my changes
• [x] I have made corresponding changes to the documentation