Related to: https://gitlab.com/gitlab-org/gitlab/-/issues/348874

Instead of using inheritance to share code among the project creation
classes, I refactor it to use composition. This away the code is a bit
more extensible and has more independent parts (less coupling).

`Import::GitlabProjects::CreateProjectFromRemoteFileService` and
`Import::GitlabProjects::CreateProjectFromUploadedFileService` was
replaced by a single entry point
`Import::GitlabProjects::CreateProjectService`.

`Import::GitlabProjects::CreateProjectService` is responsible to create
a project when the user parameters are valid. Since the user can use
different strategies to create/import a project, the requirements for
each strategy is implemented in different
`Import::GitlabProjects::Strategies::*` classes, this way the strategy
can be changed by dependency injection.

A `Import::GitlabProjects::Strategies::*` class must implement:
- initialize(current_user:, params:)
- valid? - validate the user parameters
- errors - when invalid, a ActiveModel::Errors object
- project_params - A hash with the specific strategy extra parameters to
  create the project

Also, because importing from a generic object storage and from AWS S3
have similar validations to be performed, the
`Import::GitlabProjects::Strategies::RemoteFileValidator` was created to
validate the remote file `content_length` and `content_type`.

MR: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/77259

Migrate IDE to use GlModal for discarding changes

See merge request gitlab-org/gitlab!81516

Disable clusters API if :certificate_based_clusters is disabled

See merge request gitlab-org/gitlab!81867

Docs: Correct feature flag link in upgrade page

See merge request gitlab-org/gitlab!82244

Remove the `container_expiration_policies_historic_entry` feature flag

See merge request gitlab-org/gitlab!80826

Fix jh pipeline failure of secure_binaries_ci_yaml_spec.rb

See merge request gitlab-org/gitlab!81981

Add method to query related epics of an epic

See merge request gitlab-org/gitlab!81422

- Add permissions check
- Add specs

Add hint about short expiries on token to group import

See merge request gitlab-org/gitlab!81323

* Improve security by suggesting users to use short-living tokens

Changelog: added

Update rule/yaml mode screenshots

See merge request gitlab-org/gitlab!82229

Allow tags as target of pipeline schedules

See merge request gitlab-org/gitlab!81476

Changelog: changed

Self-monitoring docs deprecation warnings

See merge request gitlab-org/gitlab!81923

Add finding failures in console

See merge request gitlab-org/gitlab!82222

Add metrics widget extension

See merge request gitlab-org/gitlab!80345

Add a proofreader

See merge request gitlab-org/gitlab!81860

Add new proofreader

See merge request gitlab-org/gitlab!75458

Deprecation MR for Self-Monitoring

See merge request gitlab-org/gitlab!81921

Ignore requirements_management_test_reports.requirement_id column

See merge request gitlab-org/gitlab!82134

Don't create partitions for geo rake tasks

See merge request gitlab-org/gitlab!82028

Migrate legacy spinner - delete milestones button

See merge request gitlab-org/gitlab!81840

Migrate legacy spinner to use
loading_icon helper. Aligns to design
system.

Changelog: changed

Add RelatedEpicLinks::DestroyService

See merge request gitlab-org/gitlab!81610

Merge branch '351211-cablett-migrate-user-namespace-maintainer-memberships-to-owner-memberships' into 'master'

Migrate personal project MAINTAINER access memberships to OWNER

See merge request gitlab-org/gitlab!80146

Link directly to scan result docs

See merge request gitlab-org/gitlab!82218

Fix `Verify SAML Configuration` button

See merge request gitlab-org/gitlab!80978

Fix the tooltip and disabled state

Changelog: fixed
EE: true

Explain that max pipelines limit has flag

See merge request gitlab-org/gitlab!81974

You can disable the max pipelines put push limit
with a feature flag.

Update definition of builds queuing feature flags

See merge request gitlab-org/gitlab!82198

Change loading state jobs tab

See merge request gitlab-org/gitlab!81568