Port "Upgrade from Babel 5 to Babel 6" to EE

See merge request !1202

Add weight to chat messages

See merge request !1172

CE upstream

See merge request !1201

squashed commit of the following:

    update dependency approval reason
    approve MIT license for wordwrap submodule
    fix failing karma test
    upgrade babel to v6
    exclude node_modules from imports-loader wrapper

Port of 27610-issue-number-alignment to EE

Closes gitlab-ce#27610

See merge request !1198

Refactored diff notes Vue app

See merge request !1199

Replaced images with the updates UX. Solving #23173

See merge request !8941

Update git clone docs

See merge request !8946

CE Upstream - Wednesday

See merge request !1191

Update Prometheus documentation

See merge request !1200

Update Prometheus documentation

Closes #27735

See merge request !9060

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Reported in https://gitlab.com/gitlab-org/omnibus-gitlab/issues/1905

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Reported in https://gitlab.com/gitlab-org/omnibus-gitlab/issues/1905

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It now relies on its Vue bundle rather than the window. Fixes some reactivity issues that was happening in EE

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Allow creating nested group via UI

See merge request !8786

Nested groups API

See merge request !9034

Fix markdown link in Omniauth docs

See merge request !9082

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