Database permissions modal - 'Share' tab

[pavish]

Related to #3686

This PR:

• Implements the 'Share' tab in the Database permissions modal.
• The components are designed to be generic inorder to be reused in Schemas and Tables pages
• Fixes a couple small unrelated bugs:
  • current_schema and current_database fields in common_data were strings instead of integers leading to always fetching schemas: 2d09537
  • Tables are returned in common_data when visiting schemas page: 3348385

Checklist

• My pull request has a descriptive title (not a vague title like Update index.md).
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• My code follows the established code style of the repository.
• I added tests for the changes I made (if applicable).
• I added or updated documentation (if applicable).
• I tried running the project locally and verified that there are no
  visible errors.

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[seancolsen]

Very cool. Nice work on this, @pavish!