Merge branch 'tr-embed-metrics-frontend' into 'master'

Embed metrics charts in issues

See merge request gitlab-org/gitlab-ce!29691

(cherry picked from commit 886a6957)

80feba93 Add ability to embed metrics
b5cdde0c Integrate latest backend changes and feature flag
330b0414 Fix jest test
c260ad82 Migrate TODOs to issues
3a822d99 Seet appropriate default
57c2eb79 Put gfm rendering behind a feature flag
cfeda009 Rename link variable
81ff8d43 Move feature spec into new MR
9d08a5dd Add devensive check on `gon` features object
ca5e00cf Add w-100 style
6e63457b Condense border into shorthand
8de8b6cf Move sidebarAnimationDuration into constants
c9936bf9 Remove extraneous default export
010bb0e3 Reword conditional logic
f4ea4c81 Simplify filter logic
a2f1b4c2 Move styling from css to utility class
da9788df Tidy up component initialization
c69a119b Avoid duplication of `embedded` param supplied by backend
be4b7a11 Remove unnecessary mount
d203980b Apply suggestion to app/assets/javascripts/monitoring/components/charts/area.vue
62ebc6e3 Use object notation
26075703 Add missing class
d9464420 Make sidebarAnimationDuration match actual sidebar animation length
83014858 Remove nextTick and compute groupData object directly
259f700b Rename variable for accuracy
f34890cc Use composite key for dashboard metric groups
92ef33a0 Fix unit test to accommodate for removal of mount call
e2f10bba Remove changelog entry as feature is behind feature flag
c6d8b271 Use graph title as key for embeds