Adds small AJAX optimistic functionality to todos.
Fixes#13656 <br/>
A good first step and boring solution. <br/>
Will make ajax call to remove each issue. <br/>
If issue is last in group of issues will refresh page. <br/>
If issues remain in group will remove row with JS. <br/>
Adds loading spinner to button and disables. <br/>
 <br/>
cc @dzaporozhets @JobV @dbalexandre
See merge request !2946
Fix bug causing dropdown to get cut off in project page
closes#14336
### Before


### After

See merge request !3257
Fix inconsistency in the header of issue and merge request pages
closes#13550
# For Issue Page
### Before

### After

# For Merge request Page
### Before

### After

See merge request !3279
Fixed alignment of download dropdown
With the new dropdown CSS - some dropdowns might look a bit odd
## Previously

## Now

See merge request !3245
Revert color for links inside gray areas
**Before**

**After**

Reverts !3147
See merge request !3276
The avatar logic has been moved from Project to Repository as this makes
caching easier. The logic itself in turn has been changed so that the
logo file names are cached in Redis. This cache is flushed upon pushing
a commit but _only_ if:
1. The commit was pushed to the default branch
2. The commit actually changes any of the logo files
If no branch or commit is given the cache is flushed anyway, this
ensures that calling Repository#expire_cache without any arguments still
flushes the avatar cache (e.g. this is used when removing a project).
Fixesgitlab-org/gitlab-ce#14363
Adjusted behavior so canceled builds tagged as allowed to fail do not fail build
## What does this MR do?
This diff changes the 'Allowed to fail' flag to also ignore canceled builds, whereas before, canceled builds could fail the suite even if they were marked as 'Allowed to fail'
dupe of !3258 to force a build
## Are there points in the code the reviewer needs to double check?
no
## Why was this MR needed?
Unexpected behavior as a user
## What are the relevant issue numbers?
## Screenshots (if relevant)

See merge request !3271
External Users
The user has the rights of a public user execpt it can never create a project, group, or team. Also it cant view internal projects.
Partially fix for both #4009 and #13938 (except the LDAP sync or a pattern to detect external users)

See merge request !3171
New branch button on issues
Creates a button which creates a branch for you, referencing the original issue in the branch name. When creating the MR the text `Closes #iid` is appended to the description field.
The button; with styling

Links to the related branches on the issue

Styled like the MR links

Please provide input on the following; the CI repo on the GDK had the following happening with the current way I implemented the matching:

Closes#3886
cc @DouweM
See merge request !2808
Fix horizontal overflow that occurs in the code tag
closes#14167
### Before Fix

### After Fix

See merge request !3255
Follow the CSS Style Guide rules for including a space after the property colon.
Fixes violations of SpaceAfterPropertyColon.
Discussed in #14299.
[ci skip]
cc: @rspeicher @jschatz1
See merge request !3260
Follow the CSS Style Guide rules for HEX colors.
Use lowercase letters and shorthand values for HEX colors where possible, in accordance with the CSS Style Guide.
Discussed in #14299.
\cc @jschatz1 @rspeicher
See merge request !3238