Fix unwanted label unassignment
## What does this MR do?
- When updating the milestone
- [x] Do not remove labels when assigning a milestone
- [x] Do not remove labels when unassigning a milestone
- [x] Do not remove labels when assigning a milestone and adding another label
- When toggling selected issues labels should be kept
- [x] Select an issue with an assigned label -> pick another label from dropdown-> unselect the issue -> select the issue again -> submit the form: Existing label should not be removed.
## Are there points in the code the reviewer needs to double check?
Labels should not be added or removed to issues when doing bulk actions unless we explicitly select a label from the dropdown
## Does this MR meet the acceptance criteria?
- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
- [x] Added for this feature/bug
- [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)
See merge request !4863
Manually create todo for issuable
## What does this MR do?
Adds a button to the sidebar in issues & merge requests to allow users to manually create a todo item themselves.
## What are the relevant issue numbers?
Closes#15045
## Screenshots (if relevant)
See merge request !4502
Revert change to search all users
## What does this MR do?
Reverts a change that allowed the user to search for all users in the author/assignee dropdown
## Are there points in the code the reviewer needs to double check?
Double check it isn't still searching all users
See merge request !4564
Loads move issue dropdown async
To keep the style of the dropdown the same as the other dropdowns in the issue form, it uses select2 rather than our new dropdowns.
Closes#16563
See merge request !4160
Issuable filtering improvements
This improves the filtering of issues and merge requests by creating a single file that encapsulates all the filtering. Previously this was done with a file for issues and a file for merge requests.
Created the ability for the text search to be done alongside other filterables. Previously because this was outside the filterable form, this wasn't possible and would instead do either filter dropdown or text filter - not both. Fixes#4252
Fixed issue with not being able to filter and sort issues without refreshing the page. Fixes#15269
See merge request !3699
This button depends on Issue#can_be_worked_on? which in turn depends on
Issue#related_branches. By rendering this button asynchronously we can
finally remove all usages of Issue#related_branches and
Issue#referenced_merge_requests from the issues "show" page.
Jacob SchatzandRobert Speicher
Douwe MaanandRobert Speicher
Phil Hughes
Stan Hu
Alfredo Sumaran
Z.J. van de Weg
Grzegorz BizonandRobert Speicher
Yorick PeterseandJacob Schatz
James Lopez