Nested groups path restrictions pt. 1

What does this MR do?

Does not allow nested group path to be one of wildcard project routes like tree, blob, commits etc. This is pt. 1 includes restrictions that does not affect existing projects.

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

no

Why was this MR needed?

To prevent routing mismatch and make it possible to differentiate git traffic and web traffic.

Does this MR meet the acceptance criteria?

• Changelog entry 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 and https://gitlab.com/gitlab-org/gitlab-ce/issues/28125#note_24871361

added 1 commit

• 5d11e3be - Restrict nested group names to prevent ambiguous routes

Compare with previous version

mentioned in issue #28125 (closed)

marked the task Added for this feature/bug 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 Branch has no merge conflicts with master (if it does - rebase it please) as completed

marked the task Squashed related commits together as completed

marked the task Changelog entry added as completed

changed title from WIP: Nested groups restrictions to WIP: Nested groups restrictions pt. 1

added 160 commits

• 5d11e3be...6b2d4947 - 159 commits from branch master
• e6cc7a0a - Restrict nested group names to prevent ambiguous routes

Compare with previous version

unmarked as a Work In Progress

changed title from WIP: Nested groups restrictions pt. 1 to Nested groups path restrictions pt. 1

@vsizov please review

LGTM

marked the task All builds are passing as completed

cc @DouweM

merged