Nested groups feature improvemetns

What does this MR do?

• Refactor and rename some methods for Namespace class
• Adds new methods to user model
• Includes nested projects in RefreshAuthorizedProjectsService

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Make code better and integrate nested groups more deeply

Screenshots (if relevant)

no

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/2772

restored source branch dz-nested-groups-access-improvements

added 1 commit

• f4d6b5c7 - Refactor Namespace code related to nested groups

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added 2 commits

• aee21eff - Refactor Namespace code related to nested groups
• 95847588 - Add User#nested_groups and User#nested_projects methods

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unmarked as a Work In Progress

changed title from WIP Add User#nested_groups method to Nested groups feature improvemetns

marked as a Work In Progress

added 94 commits

• 95847588...e553c3b4 - 92 commits from branch master
• 8ae985d8 - Refactor Namespace code related to nested groups
• 429bb00a - Add User#nested_groups and User#nested_projects methods

Compare with previous version

added 94 commits

• 95847588...e553c3b4 - 92 commits from branch master
• 8ae985d8 - Refactor Namespace code related to nested groups
• 429bb00a - Add User#nested_groups and User#nested_projects methods

Compare with previous version

added 695 commits

• 429bb00a...4b43126d - 693 commits from branch master
• 51c4b20c - Refactor Namespace code related to nested groups
• 83f0de3d - Add User#nested_groups and User#nested_projects methods

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added 1 commit

• 93e60696 - Add User#nested_groups and User#nested_projects methods

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changed milestone to %8.17

added 1 commit

• 3a104eae - Add User#nested_groups and User#nested_projects methods

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@smcgivern please review

marked the task Added for this feature/bug as completed

marked the task All builds are passing as completed

marked the task Conform by the merge request performance guides as completed

marked the task Conform by the style guides as completed

marked the task Squashed related commits together as completed

unmarked as a Work In Progress

marked the task Branch has no merge conflicts with master (if it does - rebase it please) as completed