Whenever we already deal with a User object, let's use the more specific
method avatar_icon_for_user.

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

Closes #40824

In the new navigation header, when a user uploads a custom header
logo GitLab will still show the 'GitLab' type logo. This is often
undesirable as the user may want to upload a logo with their own
name present. This change will toggle the GitLab type logo if a
custom header logo is present.

Closes #39708

some caused by webkit prefixes

fixed flexbox not working in phantomjs

This reverts commit 79f94c8d.

Revert "Combine 'turn on/off' user dropdown links into 'experimental features' link and andded 'experimental features' heading for user preferences page"

This reverts commit 75f490a4.

Combine 'turn on/off' user dropdown links into 'experimental features' link and andded 'experimental features' heading for user preferences page

Part of #34903

Fixes #34068

combine logo & wordmark
mobile improvements

only display the toggle setting in development env for now

also added the help link back into the nav bar

made the title a link back to the dashboard

[ci skip]

Start of the new navigation by redesigning just the top navigation menu.
This is only shown when a cookie is set.

Part of #32794