[9.5] Prevent a persistent XSS in the commit author block

See merge request gitlab/gitlabhq!2180

We now make use of the `content_tag` helper so that the untrusted input
is escaped and the trusted output is then automatically safe. When we
don't need to wrap the name in a `span` tag (when `avatar` is falsey),
it's treated as unsafe by default, so no further sanitization/escaping
is necessary.

[9.5] Limit `style` attribute on `th` and `td` elements to specific properties

See merge request gitlab/gitlabhq!2155

[9.5] Prevent project creation (blank, import or fork) when repository already exists on disk

See merge request gitlab/gitlabhq!2170

[9.5] Disallow the `name` attribute on all user-provided markup

See merge request gitlab/gitlabhq!2166

Fixes race condition in project uploads

See merge request !2141

Fix XSS issue in go-get handling

See merge request !2128

There are some redundancies in the validation steps, and that is to
preserve current error messages behavior

Also few specs have to be changed in order to fix madness in validation
logic.

Fixes the User Selection Display (9.5)

See merge request gitlab/gitlabhq!2177

[ci skip]

Fire system hooks when a user is created via LDAP or OAuth

Closes #37073

See merge request !13846

Fix old MR diffs

Closes #36516

See merge request !13744

Fix displaying events of removed events and events without commit messages

Closes #36685 and #36722

See merge request !13721

Remove tooltip from filtered search user

Closes #36696

See merge request !13752

Fix blank button not resetting project template value

Closes #36816

See merge request !13757

Properly encode Gitaly RawBlame request params

See merge request !13764

Support simple string LDAP attribute specifications, and search for name rather…

Closes #36841

See merge request !13776

Fix alignment of gpg status

Closes #36709

See merge request !13772

Hide group title on sidebar collapse; use more generic class for titles

Closes #36589

See merge request !13777

Stub `ForkedStorageCheck.storage_available?` by default in all specs

See merge request !13726

Fix inability to test some project integrations

Closes gitlab-ee#3194

See merge request !13729

Resolve "Badges should not be HUGE"

Closes #36496

See merge request !13635

Update GitLab Pages (9.5)

See merge request !2159

[ci skip]

Fix merge request head pipeline when pipeline has errors

Closes #36657

See merge request !13664
# Conflicts:
#	spec/services/ci/create_pipeline_service_spec.rb