Rename ENV['PROTOCOL'] to ENV['GL_PROTOCOL'] to conform to what GitLab Shell expects and make the `protocol` param in `GitAccess` mandatory.

Closes #18949

Add a new application setting, after_sign_up_text. This is text to be
rendered as Markdown and shown on the 'almost there' page after a user
signs up, but before they've confirmed their account.

Tweak the styles for that page so that centered lists look reasonable.

This reverts commit 3e991230.

# Conflicts:
#	app/models/project.rb

This reverts commit 075ace5686c63d40f7e9fa02bf37e1bd3168f7e7.

This reverts commit 78a832d0fd7ff445c707809134dbb2a42d2a9e03.

Show help only for the enabled OAuth Providers on oauth-providers-help block

aria: { describedby: help_block_id } instead of 'aria-describedby' => help_block_id

provider and not p

a more simple approach to the OmniAuth helper links for oauth-providers-help

On Application Settings Page let the user select the enabled OAuth Sign in sources instead of the disabled ones

if omniauth is enabled and if there are button_based_providers available show the disable OAuth sources

This allows users to configure the number of points stored in a single
UDP packet. This in turn can be used to reduce the number of UDP packets
being sent at the cost of these packets being somewhat larger.

The default setting is 1 point per packet so nothing changes for
existing users.

- Some views had a "Close" button. We've removed this, because we don't
  want users accidentally hiding the validation errors and not knowing
  what needs to be fixed.
- Some views used `li`, some used `p`, some used `span`. We've
  standardized on `li`.
- Some views only showed the first error. We've standardized on showing
  all of them.
- Some views added an `#error_explanation` div, which we've made
  standard.

I’ve removed everything related to the feature based on this commit:
ce08f919f34fd8849834365

Resolves #10857.

Prevent Groups to have smaller visibility than projects
Add default_group_visibility_level to configuration
Code improvements

Currently any spam detected by Akismet by non-members via API will be logged
in a separate table in the admin page.

Closes #5612

This partially reverts 6a5cd3ca - we keep the migration and add a new
migration that reverts it in order to keep migration history intact.

Introduced by me through !2005