Add pagination support to ILSD project selector

What does this MR do?

Context

The instance level environments-, operations- and security dashboard share a Vue-component to perform filtered searches and adding projects to the given dashboard.

A recent change introduced GlInfiniteScroll to handle the navigation of large result sets.

Issue

Data and methods that are needed for GlInfiniteScroll to work correctly were not added to the project selector on the security dashboard. (read issue for more information #196526 (closed))

Fix

This MR adds the needed actions and mutations to the instance level security dashboard's store to enable pagination within the project selector's results list.

Screen Capture

ILSD_project_selector

(Changed the per-page settings to 12)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Related to #196526 (closed)