Fix search tag UI issues

Fix time regions using zero hours

Allow backslash escaping in custom variables

Use correct variable name in fail text

Fix logs panel meta wrap

Explore: Hide scanning again after result was found

Explore: Logging dedup tooltips

Explore: dont pass all rows to all rows, fixes profiler

- react profiler seems to evaluate all props of all components down the tree
- this becomes slow when 1000 rows are passed to 1000 rows and their labels
- use getter function instead to ask for rows on demand

- use title attribute of toggle button group
- add descriptions for all dedup options

Explore: Fix timepicker inputs for absolute dates

- when query result was found, stop scanning
- this hides the scan status again

Add the AWS/SES Cloudwatch metrics of BounceRate and ComplaintRate.  …

- Timepicker needs to keep from and to internally as strings
for the fully controlled inputs
- make sure from and to are strings when time is reset

Remove Explore > "New tab" from sidebar

Add Google Hangouts Chat notifier.

* master: (322 commits)
  graphInterval needs to update after query execution, fixes #14364
  Explore: Parse initial dates
  Aligned styling of stats popover/box with rest of grafana & minor css refactoring
  Prometheus: Make result transformer more robust for empty responses
  Rebase fixes
  Explore: Logging line parsing and field stats
  fixed unit tests
  made unknown color theme aware and sync with graph color, some minor cleanup
  Explore: improve error handling
  use render props instead of cloneElement
  sort of a hacky way to figure if the small variation should be used for the label
  add basic button group component, using the the same label style as is
  explore logs styling
  wip: alternative level styling & hover effect
  wip: explore logs styling
  more detailed error message for loki
  If user login equals user email, only show the email once #14341
  UserPicker and TeamPicker should use min-width instead of fixed widths to avoid overflowing form buttons.  #14341
  wip: explore logs styling
  restoring monospace & making sure width are correct when hiding columns
  ...

Explore: Parse initial dates

Explore: Logging line parsing and field stats

Explore: graphInterval needs to update after query execution 

- parse dates passed from URL
- keep everything local time for now

Prometheus: Make result transformer more robust for empty responses

- we don't support tabs yet, might as well remove the entry

- some prometheus-compatible backends may return `null` instead of empty lists
- test for lists before iterating
- added tests for empty responses

Fix quota updating