* new merge request can be created by sending an email to the specific
email address (similar to creating issues by email)
* for the first iteration, source branch must be specified in the mail
subject, other merge request parameters can not be set yet
* user should enable "Receive notifications about your own activity" in
user settings to receive a notification about created merge request

Part of #32878

* master: (109 commits)
  Remove Filesystem check metrics that use too much CPU to handle requests
  Set merge_request_diff_id on MR when creating
  Add a column linking an MR to its diff
  Remove useless closeReopenReport specs
  Clarify external artifacts only working when GitLab pages is enabled
  Send SIGSTP before SIGTERM to actually give Sidekiq jobs 30s to finish when the memory killer kicks in
  Remove an exception from the git user default SSH config check
  Geo route whitelisting is too optimistic
  Update .nvmrc to current stable (v9.0.0)
  Update documentation
  Address Douwe's feedback
  Refactor responsive table styles to support nested error block
  Add changelog items
  Update specs for sudo behavior
  Move RSS and incoming email tokens from User Settings > Accounts to User Settings > Access Tokens
  Remove user authentication_token column
  Migrate user private tokens to personal access tokens
  Add sudo API scope
  Consistently use PersonalAccessToken instead of PersonalToken
  Remove User#private_token
  ...

* master: (96 commits)
  Fetch the merged branches at once
  Merging EE doc into CE
  Avoid using Rugged in Gitlab::Git::Wiki#preview_slug
  Cache commits on the repository model
  Remove groups_select from global namespace & simplifies the code
  Change default disabled merge request widget message to "Merge is not allowed yet"
  Semi-linear history merge is now available in CE.
  Remove repetitive karma spec
  Improve spec to check hidden component
  Rename to shouldShowUsername
  Add KubernetesService#default_namespace tests
  Revert "Merge branch '36670-remove-edit-form' into 'master'"
  Fix bitbucket login
  Remove duped tests
  Add path attribute to WikiFile class
  Make local_branches OPT_OUT
  Clarify the language around External Group membership with SAML SSO to clarify that this will NOT add users to GitLab Groups.
  Added ssh fingerprint, gitlab ci and pages information in an instance configuration page
  Fix the incorrect value being used to set GL_USERNAME on hooks
  Resolve "Remove overzealous tooltips in projects page tabs"
  ...

This reverts commit 915e35a2992a4e51db2ac32aac8d7a29b1f4449e, reversing
changes made to 9533786f522e358f372d8a0ec4b4990ae9d88f37.

* master: (113 commits)
  Introduce new hook data builders for Issue and MergeRequest
  Don't create todos for old issue assignees
  Start adding Gitlab::HookData::IssuableBuilder
  Include the changes in issuable webhook payloads
  Rename the `codeclimate` job to `codequality`
  Don't show an "Unsubscribe" link in snippet comment notifications
  Add QA::Scenario::Gitlab::Group::Create
  Removes CommitsList from global namespace
  Fix wiki empty page translation namespace not being removed
  Fixes mini graph in commit view
  Fix link to new i18n index page
  Update i18n docs
  Move i18n/introduction to i18n/index
  Resolve "Simple documentation update - backup to restore in restore section"
  Remove AjaxLoadingSpinner and CreateLabelDropdown from global namespace
  Move cycle analytics banner into a vue file
  Updated Icons + Fix for Collapsed Groups Angle
  Don't create fork networks for root projects that are deleted
  Remove executable permissions on images to make docs lint happy
  Sync up hard coded DN class in migration
  ...

Replaces all the explicit include metadata syntax in the specs (tag:
true) into the implicit one (:tag).
Added a cop to prevent future errors and handle autocorrection.