Add unique validation for environment_scope in clusters. Add on_environment scope for clusters. Add tests

Create has_environment_scope for centerlizing env_scope specific process. Pass environment_scope to  deployment_platform method.

Port of Resolve "Display member role per project" to EE

See merge request gitlab-org/gitlab-ee!3525

Port from CE: The API isn't using the appropriate services for managing forks

Closes gitlab-ce#40752

See merge request gitlab-org/gitlab-ee!3659

Updated geo-overview.png

Closes #4106

See merge request gitlab-org/gitlab-ee!3650

List multiple clusters EE

Closes #3734

See merge request gitlab-org/gitlab-ee!3644

Simplifying the configuration page

See merge request gitlab-org/gitlab-ee!3599

Merge branch '4242-failure-in-spec-ee-spec-services-ee-projects-hashed_storage-migrate_attachments_service_spec-rb' into 'master'

Resolve "Failure in spec/ee/spec/services/ee/projects/hashed_storage/migrate_attachments_service_spec.rb"

See merge request gitlab-org/gitlab-ee!3653

[EE] Move the "Limit conflicts with EE" doc to "Automatic CE-> EE merge"

See merge request gitlab-org/gitlab-ee!3658

Add example with number and parentheses

See merge request gitlab-org/gitlab-ee!3649

Signed-off-by: Rémy Coutable <remy@rymai.me>

Fix board filter when milestone is  predefined

Closes gitlab-ce#40654

See merge request gitlab-org/gitlab-ee!3605

Running this after
spec/services/projects/hashed_storage_migration_service_spec.rb would fail
previously, because the repository already existed on disk. As this spec expects
the repository to not exist on disk prior to being created, we should clear out
the test repos before running.