Add default related link restrictions

Related to #424880 (closed)

What does this MR do and why?

This is a follow-up to !133044 (merged) which added a table to store restrictions for work item links. This MR adds the default restrictions that will be supported for the following work item types:

Type	Can be related to	Can block	Can be blocked by
Epic	Epic, Issue, Task, Objective, Key Result	Epic, Issue, Task, Objective, Key Result	Epic, Issue, Task
Issue	Epic, Issue, Task, Objective, Key Result	Epic, Issue, Task, Objective, Key Result	Epic, Issue, Task
Task	Epic, Issue, Task, Objective, Key Result	Epic, Issue, Task, Objective, Key Result	Epic, Issue, Task
Objective	Epic, Issue, Task, Objective, Key Result	Objective, Key Result	Epic, Issue, Task, Objective, Key Result
Key Result	Epic, Issue, Task, Objective, Key Result	Objective, Key Result	Epic, Issue, Task, Objective, Key Result

As well as a migration to add the records, these changes include a database importer that populates the restrictions when seeding the default work item types. This is a very similar approach to the one used for hierarchy restrictions.

Database

• UP

❯ bin/rails db:migrate:down:main VERSION=20231005131445
main: == [advisory_lock_connection] object_id: 226640, pg_backend_pid: 51811
main: == 20231005131445 AddWorkItemsRelatedLinkRestrictions: reverting ==============
main: == 20231005131445 AddWorkItemsRelatedLinkRestrictions: reverted (0.0134s) =====

main: == [advisory_lock_connection] object_id: 226640, pg_backend_pid: 51811

Query plan (internal)

• DOWN

❯ bin/rails db:migrate:up:main VERSION=20231005131445
main: == [advisory_lock_connection] object_id: 226740, pg_backend_pid: 52309
main: == 20231005131445 AddWorkItemsRelatedLinkRestrictions: migrating ==============
main: == 20231005131445 AddWorkItemsRelatedLinkRestrictions: migrated (0.0327s) =====

main: == [advisory_lock_connection] object_id: 226740, pg_backend_pid: 52309

Query plan (internal)

How to set up and validate locally

The model validation will be added in a following MR so the unit testing should be sufficient to validate these changes.

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.